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Weather History

November 17 to November 23: This Week in Denver Weather History

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This Week in Denver Weather History

Powerful, damaging winds, heavy snow and the first official weather observation in the Mile High City highlight this week in Denver weather history.

From the National Weather Service:

14-18

In 1964…the first measurable snowfall of the season totaled 6.0 inches at Stapleton International Airport where northeast winds gusted to 32 mph on the 14th. Most of the snow…4.2 inches…fell on the 14th. This was the only measurable snow of the month.

15-17

In 1991…a strong winter storm dumped heavy snow over metro Denver. Snowfall amounts totaled 15 inches at Castle Rock and Conifer…14 inches at Morrison and Parker…12 inches in southeast Aurora…and 11.6 inches at Stapleton International Airport. Winds were light with the storm.

16-17

In 2010…the combination of heavy snow and strong winds produced dangerous driving conditions in the high country. Blizzard conditions forced the closure of U.S. Highway 6 at Loveland pass and U.S. Highway 40 at Berthoud Pass. Blowing and drifting snow forced the closure of a 65-mile stretch of Interstate 70…west of Idaho Springs. Peak wind gusts included: 68 mph atop Niwot Ridge…55 mph near Blackhawk and Gunsight…and 52 mph at Berthoud Pass. Storm totals in the ski areas west of Denver ranged from 12 to 21 inches. Northwest winds gusted to 55 mph at Denver International Airport on the 16th.

In 2010…the combination of snow and strong winds produced dangerous driving conditions in the mountains west of Denver. Near blizzard conditions forced the closure of U.S. Highway 6 at Loveland pass and U.S. Highway 40 at Berthoud Pass. Blowing and drifting snow closed a 65-mile stretch of interstate 70…between Idaho Springs and Vail Pass. Peak wind gusts included: 68 mph atop Niwot Ridge…62 mph at Loveland Pass…55 mph near Blackhawk and 52 mph at Berthoud Pass.

16-18

In 1921…heavy snowfall totaled 6.5 inches over downtown Denver. This was the only measurable snow of the month. East winds were sustained to 14 mph on the 17th.

17

In 1948…a dry vigorous cold front accompanied by north winds gusting to 60 mph produced extensive blowing dust…which briefly reduced the visibility to 1/2 mile at Stapleton Airport.

In 1993…a wind gust to 70 mph was recorded atop Squaw Mountain near Idaho Springs.

In 1994…winds gusted to 66 mph in Boulder and to 63 mph on Rocky Flats south of Boulder. West winds gusted to 49 mph at Stapleton International Airport.

In 2000…snow fell in the foothills west of Denver…mainly south of the I-70 corridor. Snowfall totals included: 8.5 inches…7 miles south of tiny town; 6 inches at Genesee; and 5 inches…11 miles southwest of Morrison. Only a trace of snow was recorded at the site of the former Stapleton International Airport.

In 2016…bands of moderate to heavy snow fell along the Interstate 70 Corridor as strong fast moving storm system moved across Colorado. Wet roads quickly became icy and snowpacked. A 20-vehicle crash involving semis kept both directions of I-70 closed near Evergreen for a couple of hours. Storm totals included:  11.5 inches…4.5 miles south-southeast of Idaho Springs; 8 inches…5 miles west of Evergreen; 7.5 inches near Conifer…with 4 to 7 inches elsewhere. At Denver International Airport…1.7 inches of snowfall was observed.

17-18

In 1869…the heaviest wind storm in 5 or 6 years raked the eastern foothills including Boulder…Denver…Georgetown… And Golden. Some hundreds of dollars in damage occurred in Boulder.

18

In 1872…fresh west winds contributed to the relative humidity dipping to zero at 2:43 pm. The maximum temperature was 54 degrees.

In 1907…heavy snowfall totaled 6.0 inches over downtown Denver. Snow fell all day. North winds were sustained to 19 mph.

In 1915…northwest winds were sustained to 42 mph with gusts as high as 48 mph. It was windy most of the day.

In 1996…high winds struck the foothills west of Denver. Wind gusts ranged from 70 to 75 mph. A few power lines were downed…but no major outages were reported.

In 1998…strong downslope winds developed during the morning. Wind gusts reached a peak of 72 mph at Jefferson County Airport near Broomfield. West winds gusted to 41 mph at Denver International Airport.

In 1999…high winds developed in and near the Front Range foothills. The strong winds downed power lines…which sparked several small brush fires. In Broomfield… Scaffolding was damaged at the Wadsworth Recreation Center…while flying rocks broke several windows at a local bank building. Peak wind gusts included: 91 mph atop Blue Mountain near Wondervu…88 mph atop the Gamow Tower on the University of Colorado campus in Boulder… 83 mph at Jefferson County Airport…81 mph at the National Center for Atmospheric Research mesa lab above Boulder…and 80 mph at Wondervu. West-northwest winds gusted to 48 mph at Denver International Airport.

18-19

In 1975…snowfall totaled only 5.5 inches and north winds gusted to 35 mph causing some blowing snow at Stapleton International Airport…while a major blizzard struck southeastern Colorado.

In 1985…4 to 7 inches of snow fell across metro Denver. Snowfall totaled 4.4 inches at Stapleton International Airport where north winds gusted to 23 mph.

In 1991…another strong winter storm produced heavy snow over metro Denver. Snowfall totaled 9.5 inches at Stapleton International Airport with 9 inches at Parker… And 8 inches in southeast Denver…Morrison…and Wheat Ridge. This second storm brought the 5 day (15th-19th) snowfall total at Stapleton International Airport to 21.1 inches. The greatest depth of snow on the ground was 13 inches on the morning of the 19th. The adverse effects of the two storms were diminished by the lack of significant winds.

Continue reading November 17 to November 23: This Week in Denver Weather History →

Weather History

November 10 to November 16: This Week in Denver Weather History

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This Week in Denver Weather History

Wintry weather is not unusual this time of year but as our look back at this week in Denver weather history shows, high winds can be just as common and oftentimes more damaging.

From the National Weather Service:

8-10

In 1985…Indian summer came to an abrupt end when a winter storm dumped 10 to 18 inches of snow in the Front Range foothills and 6 to 10 inches across metro Denver…snarling traffic and causing flight delays of up to 3 hours at Stapleton International Airport. The temperature plunged from a high of 66 degrees on the 8th to a low of only 13 degrees on the 9th…after the passage of a vigorous cold front with northeast winds gusting to 32 mph. The temperature climbed to only 19 degrees on the 10th…setting a record low maximum for the date. Snowfall totaled 7.3 inches at Stapleton International Airport with most of the snow…7.1 inches…falling on the 9th.

10

In 1897…west Chinook winds sustained to 51 mph with gusts to 60 mph warmed the temperature to a high of 64 degrees.

In 1915…southwest winds were sustained to 41 mph with gusts as high as 44 mph.

In 1955…strong winds raked the eastern foothills. A wind gust to 80 mph was recorded atop Rocky Flats south of Boulder where some damage occurred.

In 1995…snowfall totaled 6 to 9 inches in the foothills west of Denver…while only 2.2 inches of snow fell at the site of the former Stapleton International Airport. North-northeast winds gusted to 31 mph at Denver International Airport.

In 1998…strong bora winds gusting from 70 to 92 mph coupled with blowing snow created whiteout and slick black ice conditions at the base of the foothills west of Denver. State Highway 93 between Golden and Boulder and C-470… Near the Morrison interchange were closed for several hours due to multiple car accidents. Dozens of motorists were stranded until weather conditions improved. A small motor home was a total loss when it caught fire after being blown on its side by strong crosswinds. A man was injured when he was blown off a vehicle while attempting to rescue the occupants. Wind gusts included: 92 mph atop Blue Mountain near Coal Creek Canyon…83 mph atop Fritz Peak near Rollinsville…and 77 mph at Jefferson County Airport near Broomfield. West winds gusted to 36 mph at Denver International Airport.

In 2000…freezing drizzle was widespread across northeastern Colorado with the heaviest amounts near the foothills in the evening. The freezing drizzle made many highways icy and slick…which contributed to a number of traffic accidents. Some highways across metro Denver were closed at times…including portions of State Highway 119 between Boulder and Longmont and U.S. 36 between Westminster and Boulder. State Highway 93 between Boulder and Golden atop Rocky Flats became nearly impassable due to a coating of ice by late evening.

10-11

In 1911…a strong cold front produced snow and a cold wave. The temperature dropped 68 degrees from a high of 66 degrees at 12:40 pm on the 10th to a low of 2 degrees below zero at 7:15 am on the 11th. The low temperature of 23 degrees at midnight on the 10th was also the high temperature on the 11th. Northeast winds were sustained to 42 mph with gusts to 51 mph. Snowfall was only 2.5 inches.

In 1982…up to 4 inches of snow fell over the higher terrain between Denver and Colorado springs. Winds gusted to 50 mph along the foothills. Rainfall totaled 0.27 inch with only 0.1 inch of snow on the 11th at Stapleton International Airport where north winds gusted to 39 mph. Dense fog with visibilities as low as zero persisted all day on the 10th.

10-14

In 2014…an Arctic cold front on the 10th…associated with a strong storm system over the northern Rockies blasted into northeast Colorado. The temperature in Denver plummeted from the high of 64 degrees at 4:37 pm to 34 degrees by 5:53 pm. The temperatures continued to fall and dropped into the teens by early evening. The Arctic airmass remained entrenched over the region through the morning of the 14th…with the high temperatures failing to reach the teens from the 11th through the 13th. This was the first time since records have been taken in Denver…dating back to 1872…that there were three consecutive days with the maximum temperatures remained below 20 degrees in the month of November. In addition to the frigid temperatures…0.1 inch of snowfall was observed on 11th at Denver International Airport…which marked the first measureable snowfall for the season. An additional 2.2 inches of snowfall was measured on the 12th. Several temperature records were broken. A record low max of 16 degrees on the 11th broke the previous record of 19 set back in 1916. A record low max of 6 degrees on the 12th broke the previous record of 9 degrees…also set in 1916. The record low of -13 on the 12th…shattered the previous record of -4 degrees set back in 1872. Even more impressive…the record low of -14 degrees on the 13th broke the previous record of -3 degrees set back in 1916. The sudden drop in temperatures on the 10th…followed by several days of sub-freezing temperatures chilled trees to the core. The record drop in temperatures…preceded by mild fall temperatures…damaged or killed scores of trees across the Urban Corridor and Northeast Plains. At the time…the trees were not finished with the hardening process that enables them to withstand winter weather. Many were instantly flash-frozen…and some would not show signs of damage until spring of 2015. Of the 2.2 million trees in the city of Denver alone…tens of thousands were killed from the November frost. Denver estimated a citywide loss of more than 10 million dollars.

11

In 1901…a trace of rain fell in the morning…and a trace of snow fell in the afternoon. This was the only snowfall and precipitation for the month…ranking it the driest November on record…along with November of 1899 and 1949. The month also ranks as the second least snowiest November…along with Novembers in other years.

In 1903…northwest winds sustained to 45 mph with gusts to 56 mph warmed the temperature to a high of 56 degrees.

In 1912…rain changed to snow…which became heavy…and totaled 6.5 inches over downtown Denver. Precipitation was 1.02 inches…the greatest calendar day precipitation ever recorded in November. Northeast winds were sustained to 27 mph with gusts to 29 mph.

In 1919…light snow fell from an apparent clear sky during the early afternoon. The first snow was observed at about 12:40 pm and continued at least 30 minutes before clouds could be seen forming…followed by the sky becoming totally cloudy. During this time the temperature fell from 50 degrees at noon to only 18 degrees at 100 pm and plunged to 6 degrees at 5:45 pm. A low temperature of 2 degrees was recorded overnight. Northeast winds were sustained to 33 mph with gusts to 36 mph between noon and 1:00 pm behind an apparent arctic cold front. Snowfall was only 0.1 inch.

In 1949…north winds gusted to 50 mph at Stapleton Airport. A trace of rain fell. Another trace of rain on the 15th was the only precipitation of the month…making the month one of the driest Novembers on record and the least snowiest with no snow. This was the first November since 1882 without snow.

In 1959…strong northwest winds struck Boulder and the foothills causing some damage. West winds gusted to 37 mph at Stapleton Airport.

In 1995…strong downslope winds gusting to 84 mph blew out a few car windows in Boulder County. Winds gusted to 69 mph at Golden…Lakewood…and Table Mesa in Boulder. West-northwest winds gusted to 43 mph at Denver International Airport.

In 2000…heavy snow occurred in the foothills southwest of Denver and over monument ridge south of Denver. Snowfall totals included: 6.5 inches near Parker… 6 inches near Bergen Park…5 inches at Genesee and near Sedalia…and 4 inches at Coal Creek Canyon and St. Mary’s glacier. Snowfall totaled 1.6 inches at the site of the former Stapleton International Airport.

In 2003…strong downslope winds developed along the Front Range. Peak wind reports included 91 mph atop Blue Mountain near Wondervu and 75 mph in Boulder. Damaging winds downed power lines in Boulder County. North of Golden…a semi-truck was blown over by the winds near the intersection of State Highways 72 and 93 atop Rocky Flats. At the same location…blowing rocks shattered several car windows at an RTD Park and Ride. West winds gusted to 40 mph at Denver International Airport.

Continue reading November 10 to November 16: This Week in Denver Weather History →

Weather History

November 3 to November 9: This Week in Denver Weather History

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This Week in Denver Weather History

Heavy snow and damaging winds, extreme conditions typical this time of year, make repeated appearances in our look back at this week in Denver weather history.

From the National Weather Service:

2-3

In 1974…heavy snowfall totaled 6.1 inches at Stapleton International Airport where north winds gusted to 23 mph on the 3rd. Most of the snow fell on the 3rd. Maximum snow depth on the ground was 5 inches.

In 1990…a winter storm dumped 3 to 8 inches of heavy wet snow across metro Denver. In the foothills snow amounts ranged from 4 to 10 inches. Slushy snow and ice-covered roads snarled traffic. The snow…ice…and poor visibilities were blamed for numerous traffic accidents. Low clouds… Fog…and snow delayed air traffic at Stapleton International Airport for at least 90 minutes on the afternoon of the 2nd. Snowfall totaled 5.4 inches at Stapleton International Airport where north winds gusted to 21 mph.

In 2018…a powerful and moist Pacific jet stream brought a period of moderate to heavy snow and blowing snow to the mountains west of Denver with up to a foot of snow. A strong gust front generated from dissipating showers near the foothills of southeast Larimer and eastern Boulder counties pushed across the I-25 corridor and adjacent plains. As the gust front swept across Denver International Airport…a peak wind gust to 58 mph was observed from the west-northwest.

2-5

In 1946…a major snow storm dumped 30.4 inches of heavy snowfall downtown and 31.0 inches at Stapleton Airport. The winter storm closed schools and disrupted all forms of transportation in the city. The greatest depth of snow on the ground was 28 inches at the airport. The duration of the snowfall…from 4:22 am on the 2nd to 3:08 am on the 5th… A total of 70 hours and 46 minutes…is the second longest period of continuous precipitation on record and the second heaviest snowfall of record at the time in Denver. The 17.7 inches of snowfall on the 2nd and 3rd was the greatest 24- hour snowfall ever recorded during the month of November. Buses and street cars had a difficult time…and many cars were abandoned along roadsides and streets for several days. Secondary roads in rural areas were blocked for 2 to 3 weeks. Several buildings in the city collapsed or were damaged from the weight of the heavy snow. Football games were canceled. Livestock losses were high over eastern Colorado. The precipitation from this storm alone exceeded the greatest amount ever recorded in Denver during the entire month of November previously. The precipitation recorded downtown was 2.03 inches…and the previous record for the entire month of November was 1.95 inches in 1922. North winds were sustained to 26 mph on the 2nd.

3

In 1940…the longest period without snow…200 days…ended on this date with the first snow of the season…a trace…on November 4…1940. The last snow of the previous season… Also a trace…occurred on April 17…1940.

In 1959…a rare thunderstorm in November occurred around sunrise. Rainfall measured only 0.02 inch at Stapleton Airport.

In 1993…periodic high winds buffeted the foothills west of Denver. Wind gusts to 90 mph were recorded at Rollinsville in the foothills southwest of Boulder…while gusts to 85 mph were observed atop Squaw Mountain near Idaho Springs. West winds gusted to 37 mph at Stapleton International Airport.

In 1996…a rare November thunderstorm during the early evening produced 0.10 inch of rain at Denver International Airport and only 0.06 inch of rain at the site of the former Stapleton International Airport.

In 2005…strong winds developed over the urban corridor. While the damaging winds were in the Fort Collins area… High winds also developed to the south of Denver in Douglas County. Peak wind reports included 70 mph at Franktown…65 mph in Castle Rock…and 61 mph in Sedalia. West winds gusting as high as 47 mph warmed the temperature to a high of 69 degrees at Denver International Airport. Winds were strong and gusty for most of the daytime hours across metro Denver.

3-4

In 1994…a fast moving snow storm dumped 8 to 9 inches of snow on Boulder…Broomfield…and Lafayette. Snowfall totaled only 1.8 inches at Stapleton International Airport where on the 3rd east winds gusted to 20 mph and some freezing drizzle fell.

4

In 1940…a trace of snow fell in downtown Denver. This marked the start of the shortest snow season on record… 167 days…through April 19…1941…when 0.4 inch of snow fell.

In 1959…high winds caused damage in many areas of the eastern plains. In Denver…winds averaged 40 mph with gusts to 70 mph. Some damage was reported to utility lines…signs…and vehicles. Northeast winds were sustained to 30 mph at Stapleton Airport.

In 2017…strong winds developed over the Palmer Divide. Peak wind gusts included 66 and 61 mph near Monument.

4-5

In 1933…the first measurable snow of the season totaled only 2.5 inches. This was the only measurable snow of the month. Northwest winds were sustained to 27 mph on the 4th.

In 1951…heavy snowfall of 5.7 inches was measured at Stapleton Airport where northwest winds gusted to 32 mph.

Continue reading November 3 to November 9: This Week in Denver Weather History →

Weather History

October 27 to November 2: This Week in Denver Weather History

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This Week in Denver Weather History

Our look back this week in Denver weather history highlights why being prepared for winter weather is so crucial. From massive winter storms to damaging wind and deadly exposure to the elements, we have seen each in the past.

From the National Weather Service:

25-27

In 1897…a major storm dumped 13.5 inches of snowfall over downtown Denver. Rain changed to snow during the evening of the 25th and continued through mid-morning of the 27th. Most of the snow…12.0 inches…fell on the 26th when north winds were sustained to 36 mph and gusts were as high as 46 mph. Temperatures during the storm were in the 20’s and lower 30’s. Precipitation (rain and melted snow) totaled 1.21 inches.

In 2021…the minimum temperature at Denver International Airport dropped into the single digits for three consecutive mornings: 8 degrees…4 degrees and 8 degrees respectively.

26-27

In 1971…strong winds raked Boulder. At the National Bureau of Standards wind gusts to 62 mph were recorded…while in downtown Boulder winds peaked to 48 mph. At Stapleton International Airport…northwest winds gusted to 38 mph on the 26th and north winds gusted to 36 mph on the 27th.

In 1976…the first measurable snow of the season turned into a major storm. Traffic was halted for several hours on highways to the west of Denver where 8 to 12 inches of snow fell in the foothills. Snowfall totaled 7.2 inches at Stapleton International Airport where north winds gusted to 30 mph. Most of the snow…6.3 inches…fell all day on the 26th. The greatest snow depth on the ground was 5 inches on the morning of the 27th.

27

In 1980…the first snowfall of the season totaled only 1.5 inches with 0.10 inch of moisture at Stapleton International Airport where the maximum snow depth on the ground was only 1 inch due to melting. This was the only measurable precipitation of the month…making it the driest October since 1962 when only 0.03 inch of precipitation was measured.

In 1994…wind gusts to 70 mph were recorded atop Squaw Mountain…5 miles south of Idaho Springs…and at Rollinsville in the foothills southwest of Boulder. Northwest winds gusted to 28 mph at Stapleton International Airport.

27-28

In 1874…strong west winds in Boulder along with a reported tornado produced 150 dollars in damage.

In 1913…a strong cold front produced sustained northeast winds to 35 mph with gusts as high as 38 mph on the 27th. Overnight snowfall totaled 5.8 inches. Temperatures plunged to a low of 17 degrees on the morning of the 28th after a high of 60 degrees on the 27th.

27-30

In 2009…a powerful early season storm brought heavy snow to the Front Range. The combination of a deep northeasterly upslope flow coupled with abundant moisture and lift with the developing storm system produced an extended period of moderate to heavy snowfall. The heavy wet snow accumulated on trees and resulted in broken branches and scattered electrical outages. Interstates 70 and 76 were closed east of Denver. Numerous other roads and highways were shut down. The Red Cross set up numerous emergency shelters for stranded travelers. The blowing snow at Denver International Airport forced the cancellation of hundreds of flights. Schools were also closed. In the foothills storm totals included: 46 inches… 3 miles southeast of Pinecliffe; 42 inches…3 miles southwest of Conifer; 34 inches…3 miles north of Blackhawk; 30 inches at Aspen Springs and near Evergreen… 23 inches at Roxborough Park…and 20 inches…3 miles south-southeast of Morrison. Across the urban corridor storm totals included: 25 inches in Highlands Ranch; 21.5 inches near Louisville…20.5 inches in Broomfield… 20 inches at Lafayette…17.5 inches in Boulder…17 inches in Westminster…16.5 inches in Erie; 15.5 inches in Arvada and 5 miles west-northwest of Littleton…15 inches in Littleton…14 inches in Englewood…13.5 inches in Lakewood and 6 miles north of Thornton; 13.3 inches at Denver International Airport…11 inches…4 miles south of Denver; 10.5 inches…2 miles north of cherry hills village and Niwot.

28

In 1917…post-frontal snowfall totaled 6.5 inches in the city. North winds sustained to 30 mph with gusts to 33 mph caused the temperature to plunge from a high of 58 degrees to a low of 9 degrees by midnight.

In 1967…winds gusted to 65 mph in downtown Boulder…causing minor damage. South winds gusted to 32 mph at Stapleton International Airport.

In 1991…the first major snow of the season hit metro Denver as a cold arctic air mass moved over the area. Snowfall amounts across northeast Colorado ranged from 3 to 10 inches with 4.4 inches of snowfall recorded at Stapleton International Airport where north winds gusted to 22 mph. The low temperature dipped to 13 degrees.

In 1993…high winds buffeted the Front Range foothills. A wind gust to 83 mph was recorded atop Squaw Mountain…35 miles west of Denver…and a gust to 76 mph occurred near Rollinsville southwest of Boulder.

28-29

In 1993…an upper level disturbance combined with a moist upslope flow to bring heavy snow to portions of metro Denver. Snowfall amounts ranged from 5.4 inches at Stapleton International Airport to 14 inches in Boulder. New snowfall totaled 8 inches at Gross Reservoir in the foothills 5 miles southwest of Boulder. On the 28th…north winds gusted to 30 mph at Stapleton International Airport where the temperature climbed to only 25 degrees on the 29th…equaling the record low maximum for the date.

28-30

In 1971…a vigorous cold front plunged temperatures from a high of 70 degrees on the 27th to record low levels on the 29th and 30th. Snowfall totaled 3.1 inches at Stapleton International Airport where north winds gusted to 23 mph. Some freezing drizzle also fell on the 28th. Record daily low maximum temperatures of 32 degrees on the 28th and 25 degrees on the 29th were established along with a daily record minimum of 13 degrees on the 30th.

Continue reading October 27 to November 2: This Week in Denver Weather History →

Weather History

October 20 to October 26: This Week in Denver Weather History

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This Week in Denver Weather History

Temperatures continue to cool as we get further into fall and our look back at this week in Denver weather history provides some insight into the types of extreme weather that are possible this time of year. Noteworthy events include many incidences of damaging wind and some monstrous snowstorms.

From the National Weather Service:

18-23

In 2003…an extended warm spell resulted in 5 new temperature records. The high temperature of 84 degrees on the 18th equaled the record high for the date. High temperatures of 86 degrees on the 19th…83 degrees on the 21st…and 84 degrees on the 22nd were record highs for the dates. Low temperature of 49 degrees on the 23rd was a record high minimum for the date. Low temperatures during the period were in the 40’s and lower 50’s.

19-20

In 1990…an early winter storm dumped heavy snow across metro Denver. Snowfall amounts ranged from 4 to 8 inches in the foothills above 6500 feet elevation…4 to 7 inches in the Castle Rock area…and 2 to 5 inches across most of metro Denver and Boulder. Snowfall totaled 3.6 inches at Stapleton International Airport where northwest winds gusting to 48 mph kicked up some blowing dust shortly after a cold frontal passage on the 19th. However… Temperatures were warm enough to keep most roadways wet and slushy at lower elevations.

19-23

In 1906…heavy snowfall totaled 22.7 inches in the city over the 5 days. Rain changed to snow on the evening of the 19th…and snow continued through the late afternoon of the 23rd. The heaviest amount of snowfall…16.0 inches…fell from 8:00 pm on the 20th to 8:00 pm on the 22nd. The most snow on the ground was 13.3 inches on the evening of the 23rd. This was the first snow of the season and the only snow of the month. Winds during the storm were from the north at sustained speeds of 20 to 30 mph each day. Temperatures during the storm were generally in the 20’s.

20

In 1878…between 3:00 pm and 4:00 pm wind speeds averaged 48 mph with a maximum 1 minute sustained velocity to 96 mph at both 3:27 pm and 3:48 pm in downtown Denver. This is the highest sustained wind speed ever recorded in the city.

In 1986…a rare late October thunderstorm produced 3/4 inch diameter hail at Centennial Airport. Hail piled up 2 1/2 inches deep…causing some street flooding in south metro Denver.

In 2019…strong bora winds swept across the foothills and adjacent plains. Peak gusts included: 82 mph…3 miles southwest of Rocky Flats; 78 mph near White Ranch Open Space; 75 mph near Genesee and Georgetown; with 63 mph at Firestone. At Denver International Airport…a peak gust of 49 mph was observed from the west.

20-21

In 2007…a storm system brought heavy snow to the southern Denver suburbs as well as the Palmer Divide south of Denver. Storm totals included: 7.5 inches near Castle Rock…Lone Tree and Greenwood Village…with 6.5 inches at Elizabeth. Snow drifts up to 2 feet deep were observed 6 miles south-southwest of Elizabeth. In the Denver Stapleton area…2.0 inches of snow was observed.

In 2009…heavy snow developed along the Palmer Divide south and southeast of Denver as a storm system tracked across southern Colorado and northern New Mexico. Storm totals included: 15 inches…15 miles north of Elizabeth…9 inches…5 miles south-southwest of Arapahoe Park; 8 inches in Highlands Ranch…5 miles south- southeast of Sedalia; 6.5 inches…8 miles southwest of Bennett and 6 inches in Parker. At Denver international… Only 1.5 inches of snowfall was observed.

20-22

In 1936…5.5 inches of snow fell over downtown Denver. Most of the snow…4.5 inches…fell on the 20th.

21

In 1920…the rare event of snow from a thunderstorm occurred in the city during the evening. Brilliant flashes of lightning and loud peals of thunder were first noted at 7:35 pm. Light rain began falling at 8:30 pm…and light moist snow began falling a few minutes later. Some soft hail was also seen falling with the rain and snow…but both melted almost as fast as they fell. The hail only continued for a few minutes…and the rain and snow ceased about 9:40 pm. The snowfall was the first to occur in Denver this season. The amount of precipitation at the station measured only 0.01 inch…but heavier amounts were reported from other parts of the city. Snowfall was only a trace.

21-22

In 1978…heavy rain on the 21st changed to snow by daybreak on the 22nd and continued the rest of the day. This was the first measurable snowfall of the season…but totaled only 1.7 inches at Stapleton International Airport where east winds gusted to 29 mph. While only a trace of snow covered the ground…precipitation totaled 1.27 inches.

22

In 1878…winds were sustained to 42 mph.

In 1887…the first measurable snow of the season occurred… Ending the longest snow-free period in Denver…232 days… Since the last snow on March 5th.

In 1947…the first snow of the season totaled only 1.6 inches. Post-frontal north winds caused temperatures to plunge from a high of 60 degrees at midnight to a low of only 30 degrees 24 hours later. This was the only snow of the month.

In 1985…high winds gusting from 60 to 80 mph buffeted the Front Range foothills. The strongest reported wind gust was 89 mph in eastern Boulder. A treehouse east of Boulder was set on fire by a downed power line. Two people in Boulder were injured. A woman broke her arm when the strong winds knocked her to the ground. A carpenter in the city suffered a severely cut hand while he was trying to repair a roof that was being torn from a building. At Stapleton International Airport…northwest winds gusted to 41 mph.

In 2001…west-northwest winds gusting as high as 54 mph warmed the temperature to a high of 70 degrees at Denver International Airport.

22-23

In 1914…post-frontal rain changed to snow. Precipitation totaled 2.72 inches…most of which was in the form of moist snow which melted as it fell in the business section of the city. About 3 inches of snow was measured on lawns in the residential areas on the morning of the 24th. Official snowfall totaled only 0.4 inch downtown… But an estimated 8.0 inches of snow melted as it fell. North to northeast winds were sustained to 29 mph with gusts to 30 mph on both days.

In 1975…a vigorous cold front moving across metro Denver followed by strong northeast winds gusting to 52 mph produced billows of blowing dust and plunged the temperature 21 degrees in an hour. The surface visibility was reduced to 1/4 mile in blowing dust at Stapleton International Airport. The temperature cooled from a daily record high of 81 degrees to a low of 38 degrees by day’s end. The first snowfall of the season totaled 2.7 inches on the 23rd. This was the only measurable snow of the month at Stapleton International Airport.

In 1995…heavy snow fell on the Palmer Ridge south of Denver and in the foothills west of Denver where snow amounts ranged from 4 to 8 inches. Sedalia…south of Denver… Received 8 inches of snow. Winds strengthened on the plains and produced blizzard conditions…reducing surface visibilities to less than 1/4 mile. I-70 was closed from just east of Denver at Gun Club Road to the Kansas border. Ten inches of snow fell at Strasburg east of Denver where north winds at sustained speeds of 35 to 45 mph with gusts as high as 60 mph produced 2 to 4 foot drifts. Snowfall totaled only 2.2 inches at the site of the former Stapleton International Airport. North winds gusted to 51 mph at Denver International Airport.

Continue reading October 20 to October 26: This Week in Denver Weather History →

Weather History

October 13 to October 19: This Week in Denver Weather History

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This Week in Denver Weather History

Certainly snow begins to enter the equation as we get further into the season and our look back at Denver weather history for the week shows many such notable events. Others including damaging winds and even a tornado and monstrous hail storm.

From the National Weather Service:

11-13

In 1892…apparent post-frontal rainfall totaled 3.33 inches in downtown Denver over the 3 days. A trace of snow on the 12th melted as it fell. Rainfall of 2.58 inches on the 12th into the 13th was the greatest 24-hour precipitation ever recorded during the month of October. Northwest winds were sustained to 48 mph with gusts as high as 55 mph on the 12th.

12-13

In 2001…overnight peak wind gusts to 82 mph and 70 mph were measured atop Niwot Ridge and Squaw Mountain… Respectively.

12-14

In 1969…record breaking extremely cold temperatures for so early in the season occurred. The high temperature of 26 degrees on the 13th was two degrees lower than the previous record minimum temperature of 28 degrees for the date set in 1885. The high temperature of 24 degrees on the 12th exceeded the record low temperature (22 degrees set in 1885) for the date by only 2 degrees. In addition… 3 new record low temperatures for the dates were set. The low temperature dipped to 10 degrees on the 12th breaking the old record (22 degrees in 1885) by 12 degrees. On the 13th the mercury plunged to a low of 3 degrees breaking the old record (28 degrees in 1885) by 25 degrees. On the 14th the temperature reached a minimum of 4 degrees breaking the old record (25 degrees in 1966) by 21 degrees.

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In 1990…strong downslope winds stirred up clouds of dust and gravel…rattled windows…and stripped autumn-colored leaves from trees in Boulder. A wind gust to 78 mph was clocked in southwest Boulder…while a 96 mph gust was recorded in northwest Boulder. West winds gusted to only 36 mph at Stapleton International Airport.

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In 1910…light smoke from nearby forest fires drifted over the city.

In 1966…the first measurable snow of the season caused widespread damage to trees and shrubs. The heavy wet snow totaled 6.9 inches at Stapleton International Airport where north-northwest winds sustained at 20 to 25 mph and gusting to 45 mph caused much blowing and drifting snow. South and east of Denver…up to a foot of snow fell. Heavy wet snow accumulations followed by freezing temperatures and strong winds resulted in extensive damage to trees…cars… And utility lines by falling limbs. A woman was killed by a falling snow laden tree limb in Denver. Several other people received minor injuries from falling tree limbs.

In 1987…rain drenched metro Denver. The South Platte Canyon area southwest of Denver received the most with 1.11 inches at Kassler and 1.49 inches upstream at Strontia Springs. At Stapleton International Airport…0.62 inch of rain was measured…northwest winds gusted to 29 mph…and thunder was heard.

In 2007…a new 24-hour record of 2.65 inches of precipitation was set at Denver International Airport for the month of October; breaking the previous record of 2.58 inches set in 1892.

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In 1873…smoke from several large forest fires in the mountains made the air very hazy in the city.

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In 1952…the first measurable snowfall of the season left 1.2 inches of snow at Stapleton Airport. North winds gusted to 38 mph.

In 1974…rain changed to snow early in the day…but snowfall totaled only 1.0 inch at Stapleton International Airport where northeast winds gusted to 20 mph.

In 2021…very strong wind gusts developed over the higher mountain areas. Peak wind gusts atop Berthoud Pass ranged from 90 to 104 mph. At Denver International Airport…a peak wind gust to 41 mph was observed from the northwest.

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In 1871…a terrible wind occurred during a snow storm in the foothills above Boulder. Damage was minor.

In 1878…high winds reached sustained speeds of 60 mph at times.

In 1911…post-frontal northwest winds were sustained to 41 mph with gusts to 43 mph.

In 1948…strong winds struck the Boulder area. Winds averaged 50 mph at Valmont just east of Boulder. Wind gusts in excess of 60 mph were recorded at the Boulder airport. Wind gusts to 40 mph briefly reduced the visibility to 1 1/2 miles in blowing dust at Stapleton Airport.

In 1980…a rare October tornado touched down in Boulder… Damaging a vocational training building and throwing three nearby cars together damaging them extensively. A mile and half away several camper vehicles were thrown 200 feet. The storm also produced 1 inch diameter hail in the Boulder area.

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In 1928…a thunderstorm produced hail shortly after midnight on the 15th. Rain changed to snow by evening. Through the afternoon of the 16th…the heavy snowfall totaled 7.3 inches in the city. North winds were sustained to 23 mph on the 15th.

In 1984…the heaviest October snowstorm in several years hit eastern Colorado with a vengeance. The storm was known as the “Bronco Blizzard” since it occurred during a nationally televised Monday Night Football game in Denver. One to two feet of snow fell near the foothills in west metro Denver with 2 to 3 feet in the foothills. Wind gusts up to 55 mph whipped the snow into drifts as high as 4 feet. The storm closed schools…roads…and airports. I-70 was closed both east and west of Denver. I-25 was closed south to Colorado Springs. Flights were delayed for several hours at Stapleton International Airport. Power outages were widespread. Snowfall totaled 9.2 inches at Stapleton International Airport where north winds gusting as high as 40 mph caused frequent surface visibilities of 1/4 to 1/2 mile in moderate to heavy snow and blowing snow overnight. The high temperature of only 35 degrees on the 15th was a record low maximum for the date.

Continue reading October 13 to October 19: This Week in Denver Weather History →

Weather History

October 6 to October 12: This Week in Denver Weather History

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This Week in Denver Weather History

Wind is arguably one of the most annoying weather conditions and as our look back at this week in Denver weather history shows, it is often present this time of year. We also notice some decent shots of snow, including one in 2005 that brought nearly a foot to the Mile High City.

From the National Weather Service:

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In 1900…northwest winds were sustained to 40 mph with gusts as high as 50 mph in downtown Denver.

In 1903…northwest winds were sustained to 40 mph with gusts to 50 mph. The strong winds warmed the temperature to a high of 71 degrees in the city. The low reading was only 46 degrees.

In 1910…light smoke from forest fires drifted over the city.

In 1976…an arctic cold front brought light snow over the foothills above 6 thousand feet. Traffic was snarled at many locations. Only a trace of snow fell at Stapleton International Airport where rainfall totaled 0.20 inch and northeast winds gusted to 41 mph.

In 1991…the brilliant orange sunset was apparently the result of an extensive volcanic smoke layer in the upper atmosphere.

In 1994…strong west to northwest winds developed in the foothills above 9500 feet. A wind gust to 78 mph was recorded atop squaw mountain west of Denver and to 72 mph at Ward northwest of Boulder. Northwest winds gusted to 35 mph at Stapleton International Airport.

In 2011…strong winds developed in and around the Denver area ahead of an approaching storm system. At the National Wind Technology Center…peak wind gusts ranged from 79 to 92 mph during the early morning hours. Across metro Denver…the strong winds toppled a few trees and damaged patio furniture. The wind caused a few flight delays at Denver International Airport due to a partial ground stoppage of incoming flights. Peak wind reports also included: 66 mph at Cedar Point…63 mph at Denver International Airport…60 mph at Buckley Air Force Base; 59 mph at Highlands Ranch; 58 mph at Deer Trail and Rocky Mountain Metro Airport in Broomfield; 55 mph at Bennett…Centennial Airport and City Park in Denver.

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In 1903…north winds were sustained to 40 mph with gusts to 48 mph.

In 1917…post-frontal northwest winds were sustained to 45 mph with gusts to 52 mph. Rain was mixed with a trace of snow…the first of the season. Precipitation totaled 0.22 inch and included the occurrence of hail… Even though no thunder was heard.

In 1950…strong winds caused a power outage in Boulder. This was the heaviest windstorm since January. Damage was minor. Northwest winds gusted to only 35 mph at Stapleton Airport.

In 1985…strong Chinook winds buffeted the Front Range foothills. Wind gusts between 60 and 70 mph were reported in Boulder and atop Squaw Mountain west of Denver. Southwest winds gusted to 41 mph at Stapleton International Airport.

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In 1990…the season’s first snow occurred. Snowfall amounts varied from 3 to 7 inches across metro Denver. Snowfall totaled 4.0 inches at Stapleton International Airport where north winds gusted to 29 mph.

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In 1923…southeast winds were sustained to 44 mph with gusts to 47 mph. The strong winds persisted through the afternoon. The high temperature of 77 degrees was the warmest of the month that year.

In 1975…a wind gust to near 100 mph was recorded in Boulder. Frequent wind gusts to 60 mph were reported along the foothills causing only minor damage. West winds gusted to 45 mph at Stapleton International Airport.

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In 2017…an early season snowstorm produced heavy wet snow which broke branches and downed power lines. About ninety-eight thousand outages occurred in Denver and the surrounding metro area. Almost half the outages were very short…while 54210 were sustained outages that lasted longer than five minutes. Some however lasted for several hours. Snow amounts varied greatly along the Interstate 25 Corridor. West of I-25…storm totals included: 7.5 inches in Arvada…7 inches in Broomfield…6 inches Boulder and Louisville…with 5 inches at Ralston Reservoir. East of I-25…storm totals ranged from a trace to 4 inches. In the mountains and foothills…storm totals included: 12.5 inches near Genesee…10 inches at Eldorado Springs… Idledale and Nederland…with 8.5 inches near Jamestown.

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In 1910…light smoke from forest fires in the mountains was sighted over the city.

In 1982…northwest winds gusted to 49 mph at Stapleton International Airport.

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In 2005…a major winter storm brought heavy…wet snowfall to the Front Range mountains…eastern foothills…portions of metro Denver…and the palmer divide. Snow accumulations ranged from 8 to 26 inches with drifts from 3 to 4 feet in places. The heaviest snow occurred to the east and southeast of the city…closing most major highways in that area…including I-70 from Denver to Limon. The Red Cross opened four shelters for people who were stranded along I-70 in eastern Colorado. Since many trees had not yet shed their leaves…the storm caused significant tree damage. One woman in Denver was killed when a tree branch… 8 to 10 inches in diameter…snapped under the weight of the heavy…wet snow and struck her as she was shoveling her driveway. Xcel Energy reported power outages to about 35 thousand customers. Several incoming flights were delayed at Denver International Airport. Snow totals included: 16 inches in the foothills near Boulder…12 inches at Genesee and near Golden…22 inches near Watkins…19 inches near Bennett…17 inches southeast of Aurora…14 inches near Parker…13 inches near Castle Rock…12 inches in Centennial… 11 inches in Parker…and 10 inches at Denver International Airport and in Littleton. While many areas of metro Denver received heavy snow…others experienced almost entirely rain. This included west and northwest metro Denver…Boulder…and Longmont. Rainfall amounts were significant as storm totals ranged between 1.50 and 2.50 inches. The steady rainfall triggered 3 rockslides in foothills canyons. Two of the slides occurred on State Highway 119 in Boulder Canyon and the longest slide…7 feet in length…on State Highway 74 in Bear Creek Canyon at Idledale. North winds were sustained to around 23 mph with gusts to 31 mph at Denver International Airport on the 9th. The high temperature of only 34 degrees on the 10th was a record low maximum for the date. The low temperature on both days was 32 degrees.

In 2019…a vigorous winter like storm system brought intense northerly winds and the cold front blasted through the urban corridor. Peak wind gusts from 50 to 60 mph accompanied the front. Some trees in Denver were uprooted by the strong winds. Light rain and drizzle overnight…changed over to the season`s first snow during the predawn hours of the 10th. Bands of moderate to heavy snow brought 2 to 6 inches of snow in the Front Range mountains…foothills and urban corridor. The morning commute was especially hazardous as falling temperatures froze wet roads. Multiple crashes occurred including: I-25 in Denver…I-70 from Denver west to the Eisenhower Tunnel and State Highway 285 towards Fairplay. Over 300 crashes were reported in Denver and Aurora alone. After reaching a maximum temperatures of 83 degrees on the afternoon of the 9th…the temperature plummeted to 13 degrees on the 10th. A temperature change of 70 degrees…the second largest 2-day swing for the month of October in Denver weather history.

Continue reading October 6 to October 12: This Week in Denver Weather History →

Weather History

September 29 to October 5: This Week in Denver Weather History

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This Week in Denver Weather History

While it appears Denver will escape September snow, our look back at this week in weather history shows that isn’t always the case. Additionally, while not common, even early fall can bring severe weather with damaging wind, lightning and even tornadoes.

From the National Weather Service:

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In 1959…one of the heaviest September snow storms of record began as rain and changed to heavy wet snow. The storm caused heavy damage to trees and shrubbery…which were still in full leaf. The storm dumped 10.6 inches of snow at Stapleton Airport…the third heaviest September snow amount to date. Falling trees and limbs disrupted traffic…broke power and communication lines…and damaged buildings and cars. One man was killed in Denver by a falling tree limb…and four others died of heart attacks while shoveling snow or trying to move heavy tree limbs. Direct costs of the storm for cleaning up debris…repairing utility lines…and damage to buildings and other property across all of eastern Colorado were estimated to be over a half million dollars. The value of trees destroyed or damaged was estimated to exceed five million dollars. North-northeast winds gusted to 32 mph at Stapleton Airport on the 28th.

In 1985…an unusually cold air mass for this time of year settled over the area. Metro Denver received 8 to 12 inches of powdery snow. The 8.7 inches of snow that fell at Stapleton International Airport was the first measurable snow of the season and the city’s heaviest September snowfall since 1971. The snow caused flight delays of over 2 hours at Stapleton International Airport. I-70 was closed for a time west of Denver. Snow-laden tree limbs snapped over all of metro Denver…causing widespread power outages. Ten thousand people were without electricity for a time in Boulder. The morning of the 29th saw mid-winter temperatures along the Front Range. The temperature dipped to 17 degrees…the lowest temperature ever recorded in September in Denver. The high temperature of only 29 degrees on the 29th was a new record low maximum for the date and lowest ever recorded during the month of September. The low temperature of 21 degrees on the evening of the 28th set a new record low for the date. The cold weather persisted through the 1st with record minimum temperatures of 25 degrees set on the 30th and 27 degrees set on October 1st.

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In 1966…a vigorous cold front moved thru metro Denver. North winds gusting to 51 mph kicked up billows of blowing dust…which briefly reduced the visibility to 1 mile at Stapleton International Airport. The cold air caused temperatures to drop rapidly from a high of 86 degrees to a low of 46 degrees by days end.

In 1985…the lowest temperature ever recorded in September… 17 degrees…occurred. The high temperature warmed to only 29 degrees…the all-time record low maximum for the month.

In 1994…the temperature reached a high of 91 degrees at Stapleton International Airport. This was the 60th day of the year that the temperature had reached 90 degrees or more…establishing a new record at that time. The previous record of 52 “90 degree days” occurred in 1978. Only 43 “90 degree days” were recorded at Denver International Airport during 1994.

In 1995…lightning struck a couple in Aurora as they were walking in the rain. The bolt struck the umbrella the man was carrying…injuring both the man and his wife.

In 2000…late afternoon thunderstorms produced strong wind gusts to 76 mph in Westminster…to 69 mph near Boulder…and to 60 mph at Jefferson County Airport near Broomfield. No damage was reported.

In 2014…a storm system that moved through the area produced large hail and street flooding in parts of metro Denver and then spread east into the plains. The storm also caused multiple accidents. A semi became detached from a trailer… blocking traffic on westbound Interstate 70 west of Tower Road. Downed power poles blocked a roadway on CO 79 near Bennett…at mile marker 10. In addition to the damaging winds…the storms produced large hail…from nickel to golfball size across southern and eastern portions of metro Denver. The hailstorm was the most damaging of the 2014 summer season…with insured losses that topped 213 million dollars. Insurance claims included 29297 automobile claims worth more than 87.2 million dollars and 14287 property claims for 126 million dollars…ranking the storm as the eighth most expensive to hit the state. At Denver International Airport…1.01 inches of rainfall was recorded which was the greatest 24-hr rainfall for the date. In addition…a peak wind gust to 38 mph was observed at the airport

In 2015…severe thunderstorms developed over the foothills of Boulder County and Jefferson Counties…then moved south along the western suburbs of Denver. Areas north of Golden… around Lakewood and into northern Douglas County saw the heaviest rain and hail. The hail ranged in size from nickel to ping pong size

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In 1898…south winds were sustained to 41 mph with gusts to 54 mph.

In 1940…a late season thunderstorm in the city caused one lightning death.

In 1944…the month ended with a trace of rain on this date and for the month. A trace of rain also occurred on the 4th…9th…and 10th. There was no measurable precipitation for the month. The total of a trace of precipitation for the month equaled the driest September on record first set in 1892.

In 2009…a trained spotter in Coal Creek Canyon…recorded a peak wind gust to 88 mph.

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In 1959…heavy snowfall totaled 5.9 inches at Stapleton Airport. Winds were light.

Continue reading September 29 to October 5: This Week in Denver Weather History →

Weather History

September 22 to September 28: This Week in Denver Weather History

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This Week in Denver Weather History

As fall begins the weather changes and as much as we may not like it, snow is not too far off. Our look back at this week in Denver weather history shows a number of early season snow events, including one that dumped an astonishing 16.5 inches.

From the National Weather Service:

20-22

In 1902…a thunderstorm on the 20th…in advance of an apparent cold front…produced rain…hail…and northwest winds to 40 mph with gusts to 48 mph. Widespread rain developed behind the cold front and totaled 3.21 inches from the evening of the 20th through the early afternoon of the 22nd. The 2.70 inches of precipitation recorded from 800 pm on the 20th to 800 pm on the 21st is the greatest 24 hour precipitation ever recorded in the month of September. The temperature dipped from a high of 80 degrees on the 20th to a high of only 51 degrees on the 21st.

21-22

In 1870…strong winds occurred in the foothills and in Boulder and Denver.

In 1895…rain changed to snow overnight and totaled 11.4 inches in downtown Denver. This was the first snowfall of the season and the second heaviest first snowfall of the season on record. North winds were sustained to 27 mph with gusts to 30 mph on the 21st.

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In 1913…a thunderstorm produced northwest winds sustained to 40 mph with gusts to 44 mph.

In 1946…a trace of snow fell in downtown Denver. This marked the start of the longest snow season on record… 263 days through June 11…1947…when a trace of snow also fell.

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In 1873…north to northwest winds blowing almost a gale spread clouds of dust and sand into the city during the afternoon and evening. From the roof of the weather observer’s building…houses a few hundred yards away were not visible and not even the sky could be seen through the clouds of sand. The wind reached sustained speeds of 35 mph…but only 28 mph was registered for any one hour.

In 1977…wind gusts from 50 to 80 mph were reported along the foothills. A northwest wind gust to 53 mph was recorded at Stapleton International Airport.

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In 2000…the first snowstorm of the season brought heavy snow to areas in and near the foothills. While the heaviest snow fell north of metro Denver…6 inches were measured in Boulder…4 inches at both Castle Rock and Morrison…but only 0.2 inch at the site of the former Stapleton International Airport where most of the precipitation fell as rain. At Denver International Airport where drizzle and rain fell on the 23rd… Snowfall during the early morning of the 24th was estimated at 2.1 inches due to melting. The foothills west of Denver received more snow with 10 inches measured at Conifer…9 inches 11 miles southwest of Morrison… 8 inches atop Crow Hill…7 inches at Chief Hosa…and 5 inches at Ralston Reservoir.

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In 1901…northwest winds were sustained to 50 mph with gusts as high as 57 mph in the city.

In 1932…thunderstorm rainfall of only 0.11 inch was the only measurable precipitation for the month that year in the city.

In 1986…a very strong wind storm roared across metro Denver. Boulder was hit hardest. Winds peaked to 131 mph at the National Center for Atmospheric Research. This is thought to be the highest wind gust ever recorded in Boulder during September. A wind gust to 118 mph was clocked on Davidson Mesa and to 92 mph near Niwot. Gusts of 70 to 80 mph were common over all of Boulder where an estimated 70 to 90 large trees were uprooted. About a dozen of them hit cars. Two walls of a building under construction were toppled and solar panels were blown off a house. Traffic lights and power lines were downed. Damage to power equipment alone was estimated at 100 thousand dollars. Wind gusts to 87 mph at Jefferson County Airport damaged two planes. A woman was seriously injured in Boulder. She suffered a fractured skull when struck by a falling tree limb. Trees were also downed in Louisville and Lafayette. West wind gusts to 45 mph were recorded at Stapleton International Airport.

Continue reading September 22 to September 28: This Week in Denver Weather History →

Weather History

September 15 to September 21: This Week in Denver Weather History

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This Week in Denver Weather History

Denver’s famously highly-variable weather is very evident in our look back at this week in Denver weather history. Scorching hot temperatures, tornadoes, damaging wind and rain and even significant snowfall all have been seen during this time of year.

From the National Weather Service:

10-17

In 2018…the high temperature equaled or exceeded 90 degrees for 8 consecutive days; breaking the previous streak of 7 consecutive days in the month of September.

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In 2018…the high temperature equaled or exceeded 90 degrees for 9 consecutive days; marking the first time such an occurrence has taken place in the month of September. It also brought September of 2018 into a 4-way tie for most 90 degree + days in the month. Previous years included 2017…2005 and 1895. During the streak…4 record high temperatures were either tied or broken…and one record high minimum temperatures was broken.

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In 2013…a deep southerly flow over Colorado… Ahead of a nearly stationary low pressure system over the great basin… Pumped copious amounts of monsoonal moisture into the area. In addition…a weak stationary front stretched along the Front Range foothills and Palmer Divide.  This resulted in a prolonged period of moderate to heavy rain across the Front Range foothills…Palmer Divide…urban corridor. By the 14th…storm totals ranged from 6 to 18 inches… Highest in the foothills of Boulder County. The headwaters then moved down the South Platte River and caused widespread flooding with record flood stages at several locations as it made its way downstream.  The record high flood stages resulted in widespread flooding along the South Platte River basin. The flood damage encompassed 4500 square miles of the Front Range…left 7 dead… Forced thousands to evacuate…and destroyed thousands of homes and farms. Record amounts of rainfall generated flash floods that tore up roads and lines of communication… Leaving many stranded. Nearly 19000 homes were damaged… And over 1500 destroyed. Colorado department of transportation estimated at least 30 state highway bridges were destroyed and an additional 20 seriously damaged. Preliminary assessments of the state`s infrastructure showed damage of $40 million to roads and $112 million to bridges. Repair costs for state and county roads ran into the hundreds of millions of dollars. Miles of freight and passenger rail lines were washed out or submerged… Including a section servicing Amtrak`s iconic California Zephyr. The town of Lyons was isolated by the flooding of St. Vrain creek…and several earth dams along the Front Range burst or were over-topped. Floodwaters swept through Estes Park; damaged hundreds of buildings and destroyed large sections of U.S. 34 from Loveland and U.S. 36 from Lyons to Boulder. U.S. 34 suffered the most damage… With 85 percent of its roadway and bridges destroyed. In Weld County…about nearly two thousand gas wells were damaged and had to be closed off as the floodwaters inundated entire communities. Sewage treatment plants and other utilities were knocked out in a number of towns. Governor Hickenlooper declared a disaster emergency on September 13th…in 11 counties across northeast Colorado including:  Adams…Arapahoe…Broomfield…Boulder…Denver…  Jefferson…Larimer…Logan…Morgan… Washington and Weld. By the 15th…federal emergency declarations covered those counties as well as Clear Creek County. Projected losses from the flooding statewide was nearly two billion dollars in property damage…according to Eqecat… A catastrophe modeling firm.  The damage was most severe in and around Lyons and Boulder.  More than 11 thousand people were evacuated…reportedly the largest since Hurricane Katrina. President Obama declared a state of emergency for Boulder and Larimer counties.  An additional 10 counties were added on the 16th and included: Adams… Arapahoe…Broomfield…Clear Creek…Denver…Jefferson…  Morgan…Logan… Washington and Weld counties. The president also declared a major disaster specifically for Boulder County.  There were six fatalities directly attributed to flash flooding. Two 19-yr old teenagers died on the 11th…after they were swept away by floodwaters after abandoning their car on Lindon Drive in Boulder. In Jamestown…a 72-yr old man was killed when the building he was in collapsed. An 80-yr old Lyons resident died in the early morning hours of the 12th…when his truck was swept into the St. Vrain River near his home. Later on the 12th…a 79-yr old Larimer County resident was killed when she was swept away while trying to climb to safety from her home in Cedar Point. A 61-yr old cedar point resident died when her home was swept down the Big Thompson River by the floodwaters. An 80-yr old Idaho Springs resident drowned in Clear Creek when the embankment he was standing on collapsed. In Boulder…some of the monthly records broken included: one-day all-time record: 9.08 inches which shattered the previous wettest day of 4.8 inches set on July 31… 1919; one-month record of 18.16 inches…which broke the previous all-time monthly record of 9.59 inches set in May of 1995; wettest September on record which broke the previous record of 5.5 inches set in September of 1940; one-year record of 34.15 inches broke the previous wettest year of 29.93 inches set in 1995. At Denver International Airport…the total precipitation for the month of September was 5.61 inches…which was 4.65 inches above the normal of 0.96 inches. This is the most precipitation ever recorded in Denver for the month of September. Daily precipitation records included 1.11 inches on the 12th and 2.01 inches on the 14th.

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In 1921…rainfall of 0.02 inch was the only measurable precipitation of the month.

In 1976…the public reported a funnel cloud and golf ball size hail east of Parker.

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In 2000…unusually hot weather for so late in the season occurred when temperatures climbed into the 90’s setting daily record maximum temperatures on each of the 3 days. The high temperature was 92 degrees on the 15th and 95 degrees on both the 16th and 17th.

15-19

In 1906…rain on 5 consecutive days totaled 1.61 inches. A thunderstorm occurred on the 17th. High temperatures ranged from 48 degrees on the 16th to 65 degrees on the 15th. Low temperatures were in the lower to mid-40’s.

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In 1874…a blast of west winds caused minor injuries during working hours in Boulder.

In Denver…the winds veered suddenly from the southwest to the northwest around noon and increased to a maximum sustained speed of 49 mph behind an apparent cold front. The winds remained strong and backed to the west for the remainder of the afternoon.

In 2000…the record high temperature of 95 degrees at Denver International Airport established or equaled 3 different record extremes: the high temperature broke the previous record high for the day of 92 degrees set over a century ago in 1895; it marked the warmest that it has been so late in September; it also marked the 60th day during the warm season that the temperature had reached 90 degrees or more…equaling the record first set on September 29…1994.

In 2006…strong bora winds behind a pacific cold front raked the eastern slopes of the mountains and metro Denver during the afternoon. Northwest winds were sustained to 40 mph with gusts as high as 54 mph at Denver International Airport.

In 2007…a severe thunderstorm produced a peak wind gust of 67 mph…about one mile east of Bennett. At Denver International Airport…a peak wind gust of 48 mph was observed.

16-19

In 1971…a record breaking early fall snow storm caused extensive damage to trees and utility lines. The heavy wet snow occurred with little wind…but caused record breaking cold temperatures for so early in the season. Snowfall totaled 15.6 inches at Stapleton International Airport with most of the snowfall…12.0 inches…occurring on the 17th. This was the heaviest first snow of the season. The maximum snow depth on the ground was 13 inches. Record low temperatures were set on three consecutive days: 31 degrees on the 17th…23 degrees on the 18th…and 20 degrees on the 19th…which was also a new all-time record minimum for the month at that time. Record low maximum temperatures were set on 4 consecutive days: 48 degrees on the 16th…35 degrees on the 17th…40 degrees on the 18th… And 42 degrees on the 19th.

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In 1873…brisk west to northwest winds at different times during the day…generally in sudden gusts…spread a good deal of dust into the city.

In 1953…strong winds caused thousands of dollars in damage to Boulder. The winds blew for most of the day with great gustiness…and a freak twister was reported during the afternoon. Damage was minor. A thunderstorm wind gust to 40 mph caused some blowing dust at Stapleton Airport.

In 1992…a tornado touched down briefly near Bennett. No damage was reported.

In 1993…severe thunderstorms rumbled across northern portions of metro Denver. Hail as large as 1 3/4 inches in diameter fell in Brighton. Dime size hail damaged several roofs of residences in Lafayette.

In 2000…for the second day in a row…the high temperature of 95 degrees at Denver International Airport broke three record temperature extremes: the high temperature broke the previous record for the day of 94 degrees set in 1895; it marked the warmest it has been for so late in the season; it also marked the 61st day in the year that the temperature had equaled or exceeded 90 degrees…eclipsing the record equaled the previous day and first set on September 29… 1994.

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In 1901…northeast winds were sustained to 42 mph with gusts to 50 mph behind an apparent cold front.

In 1948…the low temperature cooled to only 69 degrees…the all-time record high minimum for the month.

In 1988…a strong cold front blasted metro Denver with high winds. Gusts reached 82 mph in Longmont and 81 mph at Jefferson County Airport near Broomfield where the winds flipped over and destroyed a small airplane. Wind gusts to 60 mph were recorded in Boulder and Wheat Ridge. West wind gusts to 54 mph were clocked at Stapleton International Airport. The strong winds downed trees and power lines and damaged homes and cars. A Longmont man was slightly injured…when a tree fell on top of his car.

In 1990…a slow moving thunderstorm over southwest metro Denver spawned an ominous looking funnel cloud near the intersection of Sheridan Blvd. and U.S. Highway 285. The funnel cloud nearly touched down a few times before lifting back into the main cloud. No damage was reported. Pea to marble size hail and 3/4 inch of rain fell over central and northeast Denver. Numerous streets and underpasses became flooded on Denver’s south side when the heavy runoff backed up storm sewers. Thunderstorm rainfall totaled 1.02 inches at Stapleton International Airport.

In 1993…a severe thunderstorm rolled through southeast metro Denver. Dime size hail was reported in many areas. Straight-line winds from the thunderstorm…measured by a weather spotter at 70 mph…tore the roof off 6 apartments of an apartment complex in Aurora. Heavy rain which accompanied the winds caused major damage to the apartments as well as the contents. Many trees…fences… And power poles were knocked down by the strong winds. Heavy rain flooded roadways in Denver and Aurora. Thunderstorm rainfall totaled 1.08 inches and north winds gusted to 44 mph at Stapleton International Airport where the visibility was briefly reduced to as low as 1/4 mile in heavy rain.

In 1996…a late summer snowstorm struck the northern mountains and Front Range eastern foothills. Golden Gate Canyon received 6 inches of new snow with 5 inches reported at both Nederland and Blackhawk. Thunderstorms produced heavy rain across metro Denver…which was mixed with snow by late evening. Rainfall totaled 0.83 inch at the site of the former Stapleton International Airport and 1.22 inches at Denver International Airport where northwest winds gusted to 39 mph.

Continue reading September 15 to September 21: This Week in Denver Weather History →