The end of July and beginning of August has historically been a rather active one. Looking back at the history books, deadly and damaging lightning, heavy monsoon rains and extreme heat are the dominate extremes we have seen.

From the National Weather Service:

13-5

In 2008…a streak of 24 consecutive days of 90 degrees shattered the previous record of 18 consecutive days established in 1901 and 1874. Ironically…no new single day record high temperatures were set in the month of July. In August however…a record of 104 degrees was set on the 1st…and another record of 103 degrees was set on the 2nd. In addition…a record low min of 70 degrees was set on August 2nd.

18-2

In 1987…a streak of 16 consecutive days of 90 degrees ranked 4th on the list of hot streaks. The record of 24 consecutive days was established in the summer of 2008.
26-27 in 1885…heavy cloudbursts on the palmer divide south of Denver caused flooding on Cherry Creek in the city overnight. The high water washed away street and railroad bridges and a few houses. The flood waters completely inundated the rail yards in lower downtown. This was the worst flood on Cherry Creek since May 19-20…1864…but the damage was mitigated by stream improvements and fewer structures near the channel. There was also no simultaneous flood on the South Platte River to slow the flow of water through the city. Rainfall in the city was only 0.08 inch on the 26th.

27

In 1897…an apparent dry microburst produced sustained west winds to 48 mph with gusts to 60 mph and a trace of rain.

In 1901…a thunderstorm produced north winds to 38 mph with gusts to 41 mph and rainfall of only 0.01 inch in downtown Denver. This was the only measurable rainfall of the month… Making this the driest July on record.

In 1953…an unconfirmed tornado in south Lakewood touched down briefly and abruptly dissipated. No damage was reported from the twister.

In 1955…the public sighted a funnel cloud estimated at 500 feet above the ground near the western edge of Lowry Field. Wind estimates up to 60 mph were reported in the vicinity.

In 1956…a severe thunderstorm produced 3/4 inch diameter hail and wind gusts to 48 mph at Stapleton Airport where rain fall totaled 1.08 inches.

In 1965…a tornado was sighted 21 miles south of Denver in Douglas County. No damage was reported.

In 1977…a thunderstorm wind gust to 51 mph was recorded at Stapleton International Airport. A funnel cloud was sighted by an aircraft east of Parker.

In 1982…heavy rain doused Boulder with 1 1/2 to 3 inches of rain over a short period of time…causing extensive street flooding.

In 1984…strong thunderstorms drenched several areas. Rainfall of 1.04 inches occurred in just 20 minutes at Boulder. Downpours also hit Aurora and northeast Denver… Delaying flights at Stapleton International Airport for an hour. Up to 3/4 inch of rain fell in central Aurora in 15 minutes.

In 1989…lightning hit a home in Littleton…setting a bed on fire. Damage was confined to the bedroom.

In 1994…lightning struck a furniture store in Boulder… Igniting a fire which caused major damage to the building and contents.

In 1997…lightning sparked a fire…causing extensive damage to a home in Watkins. Heavy rain caused Lena Gulch to surge 2 feet over its banks in Golden. The fire department had to rescue a man when his van stalled in high waters. High waters from swollen creeks and streams washed out bridges and several sections of road in southeast Aurora. A 200-to-300 foot section of road was washed away where Picadilly Street dips across Coal Creek. Three youths had to be rescued when they became stranded by rapidly rising water in another normally dry creek bed.

In 1999…lightning was suspected of igniting a fire which caused substantial damage to a farm in Hudson. The blaze destroyed a 10-foot by 60-foot metal pole barn…a pick-up truck…a SUV…a boat and trailer…3 four wheeler vehicles… And other farm equipment.

In 2007…a man was struck and killed by lightning while jogging at Matthews Winters Park in Morrison.

27-31

In 1956…96 percent of the total precipitation for the month of July occurred over the last five days of the month. Heavy thunderstorms produced 4.00 inches of rainfall at Stapleton Airport. This amount of precipitation in 5 days or less had been exceeded only 3 times in previous record. The last time had been in December of 1913 as snow. Considerable property damage occurred across metro Denver from flooding.

28

In 1882…intense thunderstorm lightning struck a number of places in the city…but no significant damage was reported.

In 1910…heavy thunderstorm rainfall totaled 2.21 inches in downtown Denver. Rainfall was 1.11 inches in an hour during the early afternoon.

In 1922…heavy rainfall to the south of Denver caused Cherry Creek to rise to the top of the retaining walls in the city. The creek did not flood; however…the large volume of water discharged into the South Platte River did inundate a few blocks of Globeville. Flooding also occurred along bayou creek near Franktown to the south of the city.

In 1923…thunderstorm winds were sustained to 38 mph with gusts to 52 mph.

In 1957…iridescent cirrocumulus clouds of unusual formation and brilliant color…oriented from southwest to northeast over metro Denver…were sighted by U.S. Weather Bureau observers at Stapleton Airport shortly after noon.

In 1966…heavy rains from a severe thunderstorm caused flash flooding on Deer Creek…southwest of Littleton. A child was injured when washed from a car caught in the flood waters. The flooding damaged property along the creek. Strong winds damaged several houses in suburban Littleton.

In 1970…a microburst wind gust to 52 mph was recorded at Stapleton International Airport.

In 1974…a tornado was sighted just east of Buckley Field in Aurora. No damage was reported.

In 1982…up to 2.50 inches of rain drenched an area just southwest of Denver in 30 minutes. This was the second day of heavy rain across portions of metro Denver.

In 1984…1.25 inches of rain fell in 45 minutes in Arvada. Minor flooding occurred on Bear Creek after a small dam broke.

In 1989…lightning killed two men in Arvada. They were taking wash from a clothesline when a bolt hit the older man…39… Killing him instantly. The bolt then traveled along the line…which was stretched between 2 tall trees…and hit his 26-year-old brother who died the next day.

In 1996…several weak tornadoes developed along a thunderstorm outflow boundary that moved into southern weld…northern Jefferson…and Adams counties. The tornadoes sighted near Bennett…Barr Lake…and in Arvada caused little damage. Strong thunderstorm winds downed several trees in the city of Denver and toppled several trees 7 miles west of Arvada where shingles were blown off several houses. Thunderstorm wind gusts reached 58 mph in Broomfield.

In 1997…a weak tornado touched down briefly in Parker… Damaging a greenhouse. Twenty pieces of the fiberglass roof were ripped away. Heavy rainfall in the foothills washed out some culverts in the pine and Conifer areas. Heavy rainfall spread over the plains with 4 to 7 inches reportedly falling near Hudson. Several County roads were washed out between Fort Lupton and Hudson. Several basements in the area were flooded up to the ceiling. Standing water…up to 3 feet deep…was reported in some backyards. Later in the evening…a flash flood killed 5 people and injured 40 others in two mobile home parks in Fort Collins. The torrential rainfall also caused extensive damage on the Colorado state university campus. Thunderstorm rainfall totaled 0.80 inch at Denver International Airport and 1.09 inches at the site of the former Stapleton International Airport.

In 1999…heavy rainfall…up to 3 inches an hour…triggered a massive rock and mudslide along I-70 near Bakerville. The slide area was about 200 feet wide and 20 feet deep. Several other smaller slides were also reported along the highway. As a result…I-70 was closed for nearly 25 hours in both directions until the debris could be cleared from the roadway. The blockage of I-70 was one of the longest in the history of the highway in Colorado. A severe thunderstorm produced a wind gust to 64 mph at Denver International Airport. The storm also produced 1.56 inches of rain and briefly reduced the visibility to 1/4 mile.

In 2004…a severe thunderstorm produced hail as large as 1 inch in diameter in Thornton.

In 2010…a wet microburst produced very heavy rain and torrential hail in Boulder County…in the vicinities of Caribou…Nederland and Eldora. Flash flooding washed out sections of County roads 126 and 128 near Caribou. Several large boulders had fallen across the roadways. Considerable flooding was reported in Nederland. Water was also observed running across County Road 130…between Eldora and Nederland. The hail had accumulated up to 8 inches deep near Eldora. Several vehicles were stuck in the ice…forcing the temporary closure of cr130 and the Lake Eldora ski road until snowplows could clear away the hail. Lightning strikes caused minor damage to two local businesses in Nederland. At Denver International Airport…a thunderstorm produced 0.30 inches of rain along with a peak wind gust to 38 mph.

In 2012…a tornado touched down briefly at the southeast corner of Mt. Evans near Lincoln Lake. The estimated elevation where this tornado touched down was near 12500 feet. This would make this tornado one of the highest ever observed in the U.S.

28-30

In 1889…dense smoke from forest fires in the mountains obscured the sun over the city for three days.

In 1971…a vigorous cold front late on the 28th produced northeast wind gusts to 39 mph and record breaking cold temperatures on the 29th and 30th. The temperature dipped to 47 degrees on the 29th and 43 degrees on the 30th… Setting record minimums for the dates. Upslope cloudiness along with rain and fog early on the 29th helped set a record low maximum temperature of 58 degrees for the date.

Continue reading July 27 to August 2: This Week in Denver Weather History →

Heavy rain events become more commonplace as we get further into Colorado’s monsoon season. Our look back at this week in Denver weather history contains many examples of the damage these fast-moving events can cause.

From the National Weather Service:

7-25

In 1934…a streak of 15 consecutive days of 90 degrees ranked 5th on the list of hot streaks. The record of 24 consecutive days was established in the summer of 2008.

13-5

In 2008…a streak of 24 consecutive days of 90 degrees shattered the previous record of 18 consecutive days established in 1901 and 1874. Ironically…no new single day record high temperatures were set in the month of July. In August however…a record of 104 degrees was set on the 1st…and another record of 103 degrees was set on the 2nd. In addition…a record low min of 70 degrees was set on August 2nd.

18-2

In 1987…a streak of 16 consecutive days of 90 degrees ranked 4th on the list of hot streaks. The record of 24 consecutive days was established in the summer of 2008.

19-23

In 2005…the high temperature climbed above 100 degrees on each of the 5 days with readings of 101 on the 19th…105 on the 20th…104 on the 21st…and 102 on both the 22nd and 23rd. A new record maximum temperature for the month of July of 105 degrees was set on the 20th…which also equaled the all-time record maximum for Denver of 105 degrees first set on August 8th in 1878. Daily maximum temperature records were set on each day…and the 5 day period equaled the record for the most consecutive days of 100 degrees or more first set from July 4th through 8th in 1989. The intense heat resulted in a high use of electricity for cooling purposes. The demand for electric power exceeded the supply and rolling black-outs… Each lasting about an hour…were scheduled across metro Denver during the afternoons and early evenings.

20

In 1898…an apparent thunderstorm produced sustained northwest winds to 45 mph with gusts to 51 mph.

In 1939…the high temperature reached 102 degrees in downtown Denver. This was the highest temperature recorded since August 8…1878…a period of 61 years…and the third highest temperature of record at the time. Six miles to the east… At Denver municipal airport…the maximum temperature reached 104 degrees. A dry period during mid-July…combined with low relative humidities…resulted in an unusually large number of forest fires in the mountains west of Denver.

In 1941…an afternoon thunderstorm caused two lightning deaths. The men were struck by lightning near the Denver airport.

In 1951…a thunderstorm wind gust to 54 mph was recorded at Stapleton Airport.

In 1965…heavy rain west of Denver damaged roads and bridges. Two bridges in Golden were washed out. Lightning in Denver caused some power failures and fires…mostly in the northeast section of the city. Heavy rain caused street flooding in the city of Denver. Hail as large as 1/2 inch in diameter and 0.40 inch of rain in 5 minutes were measured at Stapleton International Airport where precipitation totaled 1.09 inches. Lightning damaged a house in Littleton…and caused a power outage in Idaho Springs.

In 1973…lightning damage was reported west of Arvada.

In 1975…heavy rains caused flash flooding across metro Denver…resulting in the closing of several streets and damage to numerous homes and businesses. Hail 1/2 to 3/4 inch in diameter was reported.

In 1976…heavy thunderstorms caused flooding of streets in southeast Denver and western Arapahoe counties. A total of 3.35 inches of rain was measured at Kassler southwest of Littleton.

In 1978…a girl was injured by lightning at a country club southwest of Denver.

In 1984…heavy rain was reported just east of Buckley Field in Aurora where 1.15 inches fell in just 45 minutes.

In 1986…thunderstorms dumped heavy rain across metro Denver causing extensive street flooding…power outages…and basement flooding. The greatest recorded rainfall was 4.39 inches in Lakewood. In extreme northwest Denver…2.29 inches of rain fell in just 20 minutes. Arvada was drenched with 2.60 inches of rain…and over an inch fell in southeast Denver and adjacent sections of Aurora.

In 1990…heavy thunderstorm rains caused flash flooding in sections of Littleton where 1.20 inches of rain fell in less than 30 minutes. The deluge caused dry creek to jump its banks…causing damage to residential streets…curbs…and sidewalks. Nearly 100 vehicles were stranded for a time in fender-deep water when sewers and drainage ditches became choked with debris. The heavy runoff submerged many Littleton streets and intersections.

In 1992…strong thunderstorms moved slowly through east metro Denver…producing rainfall up to 2.50 inches in a short time. Weather spotters reported 0.75 to 1.00 inch of rain in less than 30 minutes. Many areas of southeast Denver were flooded…including I-25 where up to 6 feet of water filled some underpasses. Hail to 3/4 inch in diameter fell in Aurora.

In 1995…a tornado touched down briefly in an open field near Strasburg. Thunderstorm winds gusted to 58 mph at Centennial Airport.

In 1996…strong thunderstorm winds damaged the building of a telephone installation company in the city of Denver.

In 1998…the high temperature reached 100 degrees at Denver International Airport.

In 2006…heavy rainfall in the overland wildfire burn area caused minor flash flooding in Jamestown. The roads behind the Jamestown fire hall were washed out…when a culvert was blocked by debris. A rockslide was also reported in town.

In 2009…a severe thunderstorm produced damaging winds…large hail and very heavy rain across the western and southern suburbs of Denver. Widespread damage was observed in the cities of Arvada…Lakewood and Wheat Ridge. The intense straightline winds were the result of a wet microburst which downed hundreds of trees and snapped power poles. Wind gusts to 80 mph were reported along with hail up to 1 3/4 inches in diameter. The combination of wind and hail caused widespread damage to homes and vehicles. The damage claim estimates totaled 350 million dollars; about 32900 claims were filed for homes…while another 19500 claims were filed for vehicles. As many as 90000 homes and businesses were left without power. In some areas it took up to 3 days to completely restore electrical service. Minor injuries were reported from broken glass during the storm…but no one was hospitalized. The storm crippled the computers at the Colorado crime information center in Lakewood for nearly 3 hours. One weak tornado touched down near Parker but did no damage. In southern Weld County… Severe thunderstorms produced widespread damage over 150 square miles of farmland. In all…400 farms were directly impacted by severe weather. Damage to crops alone was estimated to 3 million dollars. At Denver International Airport…a peak wind gust to 48 mph was observed from the northeast. In addition…1.01 inches was measured at the airport.

20-23

In 1961…unusually cool weather for July resulted in several temperature records. Record minimum temperatures were set or equaled on each day with readings of 51…51…49… And 49 degrees. High temperature of only 64 degrees on the 21st was a record low maximum for the date.

20-25

In 1965…heavy showers and thunderstorms doused metro Denver with significant rain each day. Rainfall for the six days totaled 5.16 inches at Stapleton International Airport. Massive rainfall occurred on the 20th…21st…and 25th… Flooding streets and basements and causing streams to overflow. The heaviest rainfall…2.05 inches…at Stapleton International Airport occurred on the 25th.

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

Snow in July? Officially no however, it was on July 17, 1872 that a U.S. Army Signal Service weather observer reported snow in Denver. However since official record-keeping did not begin until 1882, it doesn’t count. Read more about that event and others from this week in Denver weather history below.

From the National Weather Service:

1-18

In 1874…a streak of 18 consecutive days of 90 degrees tied for second with another streak that was later set in the summer of 1901. The record of 24 consecutive days was established in the summer of 2008.

1-31

In 2012…it was the hottest July on record in Denver since weather records began in 1872. The average temperature for the month was 78.9 degrees which was 4.7 degrees above normal. There were 27 days in which the high temperature equaled or exceeded 90 degrees…which established a new record. There were also 7 days in which the temperature equaled or exceeded 100 degrees which tied the record set in 2005.

6-23

In 1901…a streak of 18 consecutive days of 90 degrees tied for second with another streak set in the summer of 1874. The record of 24 consecutive days was established in the summer of 2008.

7-25

In 1934…a streak of 15 consecutive days of 90 degrees ranked 5th on the list of hot streaks. The record of 24 consecutive days was established in the summer of 2008.

13

In 1902…west winds were sustained to 42 mph with gusts to 48 mph.

In 1910…an apparent dry microburst produced northeast winds sustained to 41 mph.

In 1961…hail as large as 1 inch in diameter was reported near Commerce City.

In 1982…a tornado touched down briefly south of Parker. No damage was reported.

In 1985…thunderstorms drenched the Highlands Ranch area of northern Douglas County with 1.50 inches of rain in just 30 minutes. Half an inch of rain fell in 15 minutes in Littleton.

In 1986…a lightning bolt struck a church steeple in Littleton…toppling it to the ground.

In 1989…thunderstorm winds blew down trees and bent a metal basketball fixture just north of Castle Rock in the surrey ridge area.

In 1993…1 inch diameter hail was measured in Lakewood.

In 1995…lightning struck and injured an assistant coach during a baseball game at Highlands Ranch south of Denver.

In 1996…3/4 inch diameter hail fell in Lochbuie with 1 1/2 inch hail measured in Brighton. Thunderstorm winds gusted to 69 mph at Bennett. The strong winds were responsible for flipping three semi-trailer trucks onto their sides along I-70…3 miles east of Bennett. A few cars were also overturned.

In 2001…heavy thunderstorm rain caused flash flooding over south metro Denver. Three inches of rain reportedly fell near the greenwood village police department in the span of 15 minutes. The heavy rain caused toll gate creek to overflow…flooding low lying areas along Parker road. Heavy rainfall also caused local flooding along streets near the Denver technology center. A severe thunderstorm dumped hail to 1 3/4 inches in diameter near Castle Rock.

In 2003…maximum temperature of 100 degrees was a record high for the date.

In 2009…severe thunderstorms produced wind gusts to 70 mph near Parker and Strasburg. At Denver International Airport…west-northwest winds gusted to 40 mph.

In 2011…severe thunderstorms produced extensive damage as they moved across the urban corridor. At Denver International Airport alone…large hail up to golfball size…very heavy rain and wind gusts to 59 mph caused substantial damage to 40 planes and stranded approximately 1500 passengers overnight. Frontier and United airlines were hardest hit as dozens of planes were taken out of service for repairs; forcing the cancellation of at least 220 flights over the next several days. Damage to the aircrafts alone was nearly five million dollars. In addition…83 cars in airport parking lots were damaged… Along with some police cars and maintenance vehicles. In Watkins…two people suffered minor injuries and 35 to 40 homes were damaged. As many as two hundred residents in a mobile home park were left homeless by the storm…forcing the red cross to open a shelter at Bennett high school. The trailer park contained 52 mobile homes…14 recreational vehicles…3 houses and a commercial building. Hailstones the size of softballs cratered the north sides of the mobile homes. Some farmers in the area said they lost as much as 85 percent of their total wheat crop. Power lines were also damaged which affected about 1200 customers in Watkins. The strong winds also flipped over a tractor- trailer rig on I-70 near Watkins Road. Insurance claims for the Watkins…Bennett and Brighton areas was estimated to be seventeen million dollars. The total damage estimate across the entire urban corridor…was near one hundred sixty five million dollars…and included 17200 automobile claims and 12600 homeowner claims. In addition…thunderstorms producing very heavy rainfall…caused flash flooding in the Four Mile Canyon burn scar west of Boulder. Three homes reportedly had water up to the windows with water flowing into structures at Fourmile Canyon road and gold run road. The heavy rain caused a 4-ft surge along Fourmile Creek through Orodell and into the entry of Boulder Creek. Several roads were affected which restricted access to the area. Roads were closed due to water and debris. Private bridges and drives were washed out and several residents were stranded and later rescued. Numerous cars were damaged in debris flows and several structures suffered flood damage but were not destroyed.

13-5

In 2008…a streak of 24 consecutive days of 90 degrees shattered the previous record of 18 consecutive days established in 1901 and 1874. Ironically…no new single day record high temperatures were set in the month of July. In August however…a record of 104 degrees was set on the 1st…and another record of 103 degrees was set on the 2nd. In addition…a record low min of 70 degrees was set on August 2nd.

14

In 1878…the temperature reached a high of 100 degrees in downtown Denver.

In 1906…a thunderstorm produced north winds sustained to 52 mph and 0.53 inch of rain in 10 minutes.

In 1912…a heavy thunderstorm cloudburst in the late afternoon combined with a similar storm to the south of the city to produce widespread flooding on Cherry Creek in downtown Denver…which resulted in two deaths and several injuries. The flooding was the worst since 1864 and covered around 3 square miles of lower downtown. Bridges along Cherry Creek were washed out and water lapped at the floor of the Broadway bridge over the South Platte River…causing authorities to declare it unsafe except for pedestrians. By nightfall… Union Depot was under 2 to 3 feet of water…and railroad and street car traffic was stalled. Those forced from their homes by the surging flood waters took refuge in the Denver auditorium. The flood waters caused great damage to the sewerage system…parkways…bridges and residences and commercial warehouses near Cherry Creek in the wholesale district. Flood damage was estimated at several million dollars. Heavy thunderstorm rainfall of 2.00 inches…of which nearly 1.75 inch fell in 30 minutes in central Denver… Was accompanied by severe thunderstorm winds sustained to 55 mph with gusts as high as 74 mph.

In 1933…thunderstorm rainfall was only 0.01 inch…but northwest winds sustained to 37 mph with gusts to 47 mph produced a dust storm for about 10 minutes during the late afternoon.

In 1967…heavy rain flooded areas of north and west metro Denver…and high water closed street intersections in the city. Crops were damaged…and 200 chickens drowned by flooding northwest of Denver where farm buildings and irrigation facilities were also damaged.

In 1969…a thunderstorm wind gust to 51 mph was recorded at Stapleton International Airport.

In 1975…heavy rains caused locally heavy flash flooding along Niver Creek south of Thornton and in other parts of north metro Denver. Over 40 thousand dollars in damage to public property was reported…and numerous homes and yards were damaged.

In 1986…thunderstorm winds blew down a power line in west- central Jefferson County. The storm…as it moved into Denver…snapped tree limbs and damaged a fence near Washington Park. Wind gusts in the area were estimated at 80 to 85 mph.

In 1990…thunderstorm wind gusts to 58 mph were recorded at Buckley Field in Aurora. No damage was reported. Winds gusted to 44 mph at Stapleton International Airport.

In 1993…a severe thunderstorm moved across southern sections of metro Denver. Dime size hail fell in Lakewood…and hail up to one inch diameter was measured at Cheery Creek Reservoir. Later in the afternoon…hail to one inch diameter fell in Golden and Arvada.

In 1994…hail to 1 1/4 inches in diameter fell north of Bennett.

In 1998…dry microburst winds estimated to 70 mph snapped tree branches up to 4 inches in diameter in Brighton where some road signs were twisted and blown down. At Denver International Airport…dry microburst winds gusted to 61 mph.

In 1995…thunderstorm winds gusted to 62 mph near Strasburg.

In 2001…a severe thunderstorm dumped hail to 3/4 inch in diameter in the foothills about 10 miles northwest of Golden.

In 2011…severe thunderstorms in the Denver metropolitan area produced very heavy rain…large hail and damaging winds. The strong winds toppled a few trees and the heavy rain caused street flooding and minor flash flooding. Several cars were stranded at the intersection of Santa Fe Drive and Oxford…and near Broadway and U.S. Highway 285. A 16-yr old teenager was seriously injured when he tried to retrieve a ball along the banks of West Toll Gate Creek. He was pulled from the swollen creek and died several days later. Hail up to one inch in diameter was reported around the area. The thunderstorms also produced frequent lightning. One strike sparked a fire at aspen academy…a private school in Greenwood Village. Most of the damage was confined to the roof and attic. In Englewood…a 40-ft tree was blown into a house and knocked down some power lines. At Denver International Airport…a severe thunderstorm produced sustained winds of 47 mph and a peak wind gust to 68 mph.

14-15

In 1985…thunderstorms dumped heavy rain and hail at numerous locations along the Front Range from Denver north. Some of the heaviest rain fell in northern and western suburbs of Denver. Up to 2.6 inches of rain drenched Arvada…and Thornton was soaked with 2 inches in 45 minutes. At least 5 homes in Arvada suffered extensive damage from water and mud…and many streets and basements were flooded. In southern Jefferson County…11 homes were struck by lightning.

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

This week in Denver weather history shows record-setting heat, flooding rains, a few tornadoes and dangerous lightning. It must be July.

From the National Weather Service:

29-15

In 2000…the 29th marked the beginning of a near record hot streak for metro Denver. The high temperatures…as recorded at Denver International Airport…exceeded the 90 degree mark for 17 consecutive days from June 29th through July 15th. The record of 24 consecutive 90 degree or above days was set from July 13th through August 5th…2008.

1-18

In 1874…a streak of 18 consecutive days of 90 degrees tied for second with another streak that was later set in the summer of 1901. The record of 24 consecutive days was established in the summer of 2008.

1-31

In 2012…it was the hottest July on record in Denver since weather records began in 1872. The average temperature for the month was 78.9 degrees which was 4.7 degrees above normal. There were 27 days in which the high temperature equaled or exceeded 90 degrees…which established a new record. There were also 7 days in which the temperature equaled or exceeded 100 degrees which tied the record set in 2005.

4-8

In 1989…one of the most intense heat waves on record roasted metro Denver. The temperature reached 100 degrees or more on 5 consecutive days. The city had previously never recorded more than 2 straight 100-degree days since records began in 1872. Water and electricity usage reached all-time highs. The heat wave created extremely dry weather conditions…which contributed to a major forest fire in Boulder Canyon on July 9th. The temperature reached 103 degrees on the 8th…and the mercury climbed to 101 degrees on both the 4th and 5th…and to 102 degrees on both the 6th and 7th. The low temperature of 68 degrees on the 8th equaled the record high minimum for the date.

6

In 1876…the high temperature reached 101 degrees in downtown Denver.

In 1943…four people were injured by lightning in Denver during a severe early evening thunderstorm. At least two houses were set on fire by the lightning. One house had $1500 in damage and the other $1000.

In 1959…wind and lightning caused some damage in metro Denver. Wind gusts to 67 mph blew down power lines…signs… And trees. Lightning struck several transformers…leaving many areas without power.

In 1971…a microburst wind gust to 68 mph was recorded at Stapleton International Airport.

In 1973…the temperature reached a high of 103 degrees. This was the second consecutive day with a temperature of 100 degrees or more.

In 1984…a weak tornado moved through eastern Aurora. About 10 homes sustained minor damage to roofs; some sections of fence were thrown more than a block. Soft hail…an inch in diameter…fell over central Aurora…and 1.35 inches of rain fell in just 45 minutes…5 miles east of Buckley Field. Torrential rain and hail stopped traffic on I-225 in central Aurora for 15 minutes. Street flooding was widespread. A wind gust to 57 mph was recorded in southeast Aurora. A wind gust to 66 mph was reported at Front Range airport near Bennett. Northwest winds gusted to 44 mph at Stapleton International Airport where only 1/8 inch hail fell.

In 1986…one inch diameter hail fell near Conifer in the foothills west of Denver. The storm produced 1.50 inches of rain in an hour with a storm total of 2.15 inches. Nearby buffalo creek was drenched with 0.80 inch of rain in just 10 minutes.

In 1996…3/4 inch diameter hail fell in Bennett…east of Denver. Hail…as large as 1 1/2 inches in diameter… Damaged several vehicles in the parking lot of the Colorado speedway race track near Dacono north of Denver. Several trees were also damaged.

In 2001…a severe thunderstorm wind gust to 59 mph was recorded at Denver International Airport…along with small hail.

In 2009…hail up to 1 inch in diameter was observed near Longmont.

In 2010…heavy rain caused flash flooding near Interstate 70 at the Byers exit. Two feet of water was observed moving across the bottom of exit ramp. One car was washed into a tree but no one was injured. In addition…severe thunderstorms produced hail up to 1 1/2 inches in diameter near Franktown. At Denver International Airport…only 0.01 inches of rainfall was observed. A peak wind gust to 45 mph from the west was also recorded.

6-23

In 1901…a streak of 18 consecutive days of 90 degrees tied for second with another streak set in the summer of 1874. The record of 24 consecutive days was established in the summer of 2008.

7

In 1905…a thunderstorm produced sustained northeast winds to 40 mph…but only a trace of rain.

In 1933…heavy cloudbursts during the afternoon in the Idledale area and on Saw Mill Gulch caused flash flooding on Bear Creek resulting in 7 deaths. Flooding in Morrison was compounded when a wall of water as high as 15 feet swept down Mount Vernon Creek. The flooding caused extensive damage to the Bear Creek Canyon Highway.

In 1959…wind gusts to 45 mph at Stapleton Airport…but higher in other areas…damaged power lines and buildings and caused widespread minor damage from falling trees and broken limbs. A field house under construction at Adams County high school in Commerce City sustained severe damage.

In 1963…farm buildings east of Boulder were possibly damaged by a small tornado as there were unconfirmed reports of a funnel cloud in the area.

In 1967…a storm of cloudburst proportion caused damage from flooding in southwest and south Denver. Unofficial reports indicated rainfall of 2.00 inches in 30 minutes and more than 3.00 inches total from the storm. Streets and buildings were flooded by the heavy run-off. Hail in some areas contributed to flooding by blocking storm drains. Water accumulated 12 to 14 feet deep in several underpasses and some street intersections. A young woman drowned when she tried to cross a flooded street and was swept off her feet and trapped under a parked car. Water reached a depth of 5 feet in the street. Police rescued numerous stranded motorists. The roof and wall of a flat roofed store building collapsed under the weight of deep water on the roof. Cars were washed over curbs in many areas. In southwest metro Denver…100 to 150 homes were flooded. Hail caused damage in other areas of Denver and in Aurora. Wind toppled trees in several areas. Snowplows were called out to clear hail from some highways and runways at Stapleton International Airport. Lightning damaged trees and power lines and started a fire…which extensively damaged an automobile dealership. Thunderstorm rainfall totaled 0.83 inch at Stapleton International Airport.

In 1981…severe thunderstorms produced 3/4 inch hail over east Denver. About 1 1/2 inches of rain fell in Littleton. Thunderstorm winds gusted to 45 mph at Stapleton International Airport.

In 1983…tennis ball size hail fell about 5 miles north of Boulder; it was soft and caused no damage.

In 1987…a weak tornado touched down in Castle Rock. Several weak tornadoes were observed in the area. No damage was reported.

In 1988…lightning struck a sign at a bank near Louisville… Damaging it and causing a smoldering fire that resulted in smoke damage to the bank and an adjacent building. Heavy thunderstorm rain…accompanied by 1/2 inch diameter hail at Stapleton International Airport…briefly reduced the visibility to 1/4 mile. Rainfall totaled 1.41 inches… But 1.12 inches fell in 32 minutes.

In 2001…severe thunderstorms dumped large hail across north metro Denver. Hail to 1 3/4 inches in diameter fell near Erie with 7/8 inch hail measured in Thornton.

In 2004…a 9-year-old boy was struck by lightning while at a playground in Arvada. The umpire at a nearby baseball game…along with 2 passers-by…administrated CPR and resuscitated the boy who had quit breathing. The boy suffered first and second degree burns…but was released from the hospital in less than 24 hours. A dry microburst over Denver International Airport produced a peak wind gust to 61 mph.

In 2006…up to 3 inches of heavy thunderstorm rainfall in the Hayman wildfire burn area produced destructive flash flooding along west creek between the towns of Deckers and Westcreek in southwest Douglas County. Horse Creek…which drains into west creek…swelled from a normally small creek into a raging torrent…25 to 30 feet deep and 300 feet wide. The wall of water damaged or destroyed about 30 sections of a 5 mile stretch of State Highway 67…which parallels West Creek. Several homes were extensively damaged or destroyed. No injuries were reported…but several people had to be rescued…due to extensive damage to access roads and bridges in the area. Reconstruction was estimated at 13.3 million dollars.

In 2011…heavy rain associated with a wet microbursts produced over 3 inches of rain in 90 minutes across southeast Denver. In Denver…some underpasses were flooded with several feet of water which stranded motorists. As a result…the fire department conducted at least 10 water rescues. Some basements were inundated with up to 4 feet of water which caused extensive flood damage. The Platte Valley and Western Model Railroad Club’s model train display in Union Station was also damaged when 3 to 4 inches of mud and water spilled over some of the command and control systems. Several display modules and scenery pieces in a storage room were also damaged. The entire display spanned more than one thousand feet of track in a room that was once used as the jail at Union Station in the 1900s. Urban and small stream flooding was reported across the surrounding Denver suburbs. The storm left about 28000 Xcel customers without power when the storm snapped trees and power lines. In addition…heavy rain produced flash flooding in the Four Mile Canyon burn scar. Four debris slides occurred along Four Mile Canyon Drive…including one that was 100 yards wide and 4 feet deep. Several rockslides were reported in Lefthand and Boulder canyons. At Denver International Airport…1.04 inches of rain was observed. A peak wind gust of 46 mph from the southeast was also observed.

In 2012…heavy rain produced flash flooding in Boulder County near Jamestown. James canyon drive was closed after heavy rain washed out a section of the roadway. Heavy rain washed out a section of magnolia road…east-southeast of Nederland. Nearby…a trained spotter 4 miles east-northeast of Nederland… Measured 2.20 inches of rainfall. Flash flooding was also reported in the Fourmile burn area along Summerville road. In Dacono…in southern Weld County…the Colorado Department of Transportation used snowplows to clear standing water…up to 6 inches deep…from a section of Interstate 25. The interstate was closed in both directions for nearly two hours. South of the Denver…in central Douglas County…flash flooding was reported near Perry Park…where 2.5 inches of rain fell in one hour.

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