Our weekly look back at Denver weather history always has interesting items but this week one stands out in particular. Denver has never officially recorded snow during the month of July. However, before official records began in 1882, the U.S. Army Signal Service weather observer reported snow on July 17, 1872!

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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.

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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.

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In 1997…an extended hot spell resulted in 3 temperature records being set. The maximum temperature reached 98 degrees on each of the days…setting records on the 16th and 18th. The low temperature of 71 degrees on the 17th was a record high minimum for the date. The high temperature reached 100 degrees on the 17th at the site of the former Stapleton International Airport.

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In 1872…the U.S. Army Signal Service weather observer recorded snowfall during the early morning hours in the hand written daily weather journal: “rain commenced at 1:30 a.m. changing about 3 a.m. to snow & in about half an hour to rain again; it continued until 6 a.m.” this is the only recorded occurrence of snowfall in Denver in July…but this report is not included in the “official” station snowfall records…which did not begin in Denver until January 1…1882. The low temperature on this morning was 45 degrees…which is sufficiently cold for the occurrence of light stratiform snowfall.

In 1918…a thunderstorm produced hail to an inch in depth on the ground. The stones varied in size from a small cherry stone to nearly 1/2 inch in diameter. Not much permanent damage was done to crops. Precipitation totaled 0.40 inch…and northeast winds were sustained to 25 mph with gusts to 28 mph.

In 1971…the temperature reached a high of 101 degrees at Stapleton International Airport.

In 1983…3/4 inch diameter hail fell at Lafayette…while golf ball size hail pelted Brighton and Northglenn where funnel clouds were also sighted.

In 1986…1 1/2 inches of rain fell in an hour and 15 minutes in southeastern Aurora. Thunderstorm rainfall totaled 0.89 inches at Stapleton International Airport.

In 1987…a small tornado was sighted near Watkins…in the vicinity of Front Range airport.

In 1997…lightning ignited an oil well tank holding 10 thousand gallons of oil…16 miles northwest of Bennett. About 200 acres of grassland burned before the fire could be extinguished. A dry microburst produced a wind gust to 52 mph at Denver International Airport.

In 2000…an estimated 2 inches of rain fell in less than an hour…causing two secondary roads in buck and miller gulches in the hi meadows fire burn area to wash out. Water also covered Jefferson County road 68 which connects to Bailey. Homeowners in pine valley estates attempted to divert some of the runoff by piling stacks of hay on the hillside above their homes. Torrential rainfall…up to 3.50 inches an hour…caused flash flooding along Whiskey Gulch near Elizabeth. Several roads were washed out and basements flooded during the storm. Along County Road 13… About 6 miles north-northwest of Elizabeth…rushing water washed away a 15-foot section of the road. The floodwaters forced debris and mud into four huge culverts…sending water over the road. At Denver International Airport…an United Airlines ground crew worker was struck by lightning as she was loading a Boeing 747 jumbo jet. The woman was injured when lightning either hit the jet or the loading equipment that she was working near. The 25-year-old woman received only minor injuries.

In 2006…outflow from severe thunderstorms to the southeast of metro Denver produced southeast sustained winds to 35 mph with gusts as high as 52 mph at Denver International Airport during the late evening.

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In 1874…the temperature climbed to 90 degrees or more for the 18th consecutive day…setting a record. The record was equaled from July 6th through the 23rd in 1901.

In 1902…a thunderstorm produced northwest winds sustained to 45 mph with gusts to 48 mph along with rain and hail. Total precipitation was 0.53 inch.

In 1911…a shower produced north winds sustained to 44 mph.

In 1958…1 1/2 inch diameter hail fell 9 miles west-southwest of Stapleton Airport.

In 1981…a thunderstorm bombed Evergreen with about 2 inches of rain in 45 minutes. A heavy hailstorm left 5 to 7 inches of hail on the ground in some places and stopped the Colorado Open golf tournament at Hiwan.

In 1985…over 2 inches of rain doused the southwest suburbs of Denver. Street flooding occurred in the Montbello area of northeast Denver.

In 1992…nickel size hail fell across central Douglas County near Castle Rock and Sedalia. One inch diameter hail fell in Castle Rock.

In 1993…thunderstorm winds gusted to 60 mph at Strasburg east of Denver.

In 2004…heavy thunderstorm rainfall caused flooding over parts of the Virginia Canyon Road near Idaho Springs. Several sections of the roadway were washed out. The road was closed temporarily for repairs.

Continue reading July 17 to July 23 – This Week in Denver Weather History →

Our look back at this week in Denver weather history demonstrates why July is considered the Mile High City’s stormiest month. Many instances of flooding rains, damaging wind and hail and dangerous lightning are seen in our past.

From the National Weather Service:

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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.

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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.

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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.

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In 1980…a series of severe thunderstorms hit metro Denver… Dumping heavy rain and producing a spectacular lightning display lasting for several hours. A number of homes were damaged by lightning. Winds gusted to 60 mph at Stapleton International Airport where about half an inch of rain fell in just 10 minutes along with 1/4 inch diameter hail. The evening thunderstorms continued into the early morning hours with total rainfall of 1.35 inches at Stapleton International Airport.

In 1998…thunderstorm rainfall totaled 2.04 inches at the site of the former Stapleton International Airport.

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In 1878…a lunar rainbow was observed during a light mist and fog.

In 1895…the temperature warmed to a high of only 53 degrees… The all-time record lowest maximum temperature for the month of July.

In 1967…golf ball size hail damaged aircraft at Jefferson County Airport near Broomfield.

In 1983…two people were injured when struck by lightning just southwest of Morrison. A man was injured when he was swept downstream by a flash flood on a tributary of clear creek in the canyon 8 miles west of Golden. Heavy thunderstorm rains caused mudslides which closed several roads. Rainfall amounts included: 1.75 inches in 20 minutes in southeast Denver…1.26 inches in 35 minutes in Boulder…2.14 inches in 2 hours in Lakewood…1.70 inches in 45 minutes in Aurora…and 1.25 inches in 30 minutes atop Floyd Hill in the foothills west of Denver.

In 1992…storm spotters reported 3/4 inch diameter hail near the construction site of the new Denver airport just northeast of the city.

In 1995…microburst winds toppled a pine tree 60 feet high and 2 feet in diameter in Denver. The tree fell and injured a man nearby. Microburst winds to 59 mph broke the glass on a door at the national weather service forecast office at the site of the former Stapleton International Airport.

In 1998…thunderstorm rainfall totaled 2.35 inches at Denver International Airport.

In 2000…three children were injured…one critically…when lightning hit a nearby tree at panorama point atop Flagstaff Mountain just west of Boulder. Lightning hit the tree…entered the ground…then struck the children. Lightning sparked a grassfire that burned about 50 acres at the Rocky Flats Environmental Test Facility. Also… Lightning sparked at least 6 fires in the Hudson and Keenesburg areas as thunderstorms…accompanied with heavy rain…large hail…and tornadoes…moved through southern Weld County. Over 2 inches of very heavy rain caused flooding along an I-76 exit ramp near Keenesburg. The fire department rescued 15 stranded motorists as high water inundated sections of the exit ramp and adjacent highway. Basements were also flooded in Keenesburg. One home reportedly had 7 feet of standing water in the basement before the rain subsided. A weak tornado (F0) touched down briefly near Brighton…but caused no damage.

In 2001…a severe thunderstorm dumped 7/8 inch diameter hail in wheat ridge.

In 2002…severe thunderstorms pelted the southern suburbs of metro Denver with large hail. Hail as large as 3 inches in diameter fell 6 miles southeast of Parker. Other large hail reports included 2 inch diameter hail around centennial airport and 3/4 inch hail near Sedalia and Deckers. Hail as large as 3/4 inch was also reported in Broomfield. Runoff from heavy thunderstorm rainfall in the Hayman fire burn area flooded lost creek ranch with up to 18 inches of water just off State Highway 126. Floodwaters damaged a very expensive rug in the lodge. A driveway to a residence was washed away. In Douglas County…runoff damaged forest access roads in the Turkey Creek drainage.

Continue reading July 10 to July 16 – This Week in Denver Weather History →

In our July weather preview we discussed how the month is not only Denver’s hottest but also its stormiest. Our look back at this week in Denver weather history helps to illustrate that fact. We start seeing 100+ degree days as well as many of the types of fast moving thunderstorm events expected this time of year.

From the National Weather Service:

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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.

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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.

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In 1874…the temperature climbed to a high of 101 degrees in downtown Denver.

In 1881…the all time highest recorded daily minimum temperature of 77 degrees occurred in the city. This was also the highest daily minimum temperature ever recorded in July.

In 1885…a severe thunderstorm produced hail the size of hazel nuts…which fell with great force. A telegraph pole in west Denver was struck by lightning and shattered to pieces.

In 1955…a brief microburst wind gust to 61 mph was recorded at Stapleton Airport.

In 1960…a major hail storm caused 1.5 million dollars in damage across metro Denver. The heaviest damage occurred in south Denver…Englewood…Littleton…and Golden from wind- driven hail as large as golf balls and heavy rain which caused flooding. Winds were estimated at 60 to 70 mph. Rainfall was estimated at 2 to 3 inches. Hail accumulated 3 to 4 inches deep in some sections. Hail carried by flood waters drifted 3 to 4 feet deep. An Englewood policeman was injured when hail broke the windshield of his car. One inch of rain in 10 minutes…and heavy hail damage were reported in Parker. At some places the hail from the storm was still on the ground the next morning.

In 1967…large hail stones from 1 3/4 to 2 1/2 inches in diameter damaged cars and buildings in southwest Denver and Littleton where hail drifted to depths of 3 to 4 feet. The hail caused a great deal of damage…and streets were flooded by heavy rain over many sections of west metro Denver. At centennial race track near Littleton…a few hail stones were as large as tennis balls. Large hail broke the windshield on a Littleton police car. Golf ball to tennis ball size hail fell in the vicinity of Arapahoe road and south Broadway. One inch diameter hail fell at the intersection of orchard and south university. Golf ball size hail fell in Broomfield. Hail in Westminster was measured from 1 to 1 1/4 inches in diameter. Tornadoes were sighted by the public near Cheery Creek Reservoir… north of Commerce City…and in Arvada…but caused no reportable damage.

In 1993…high winds developed behind a strong cold front along portions of the Front Range. While the strongest winds were reported north of metro Denver…the winds blew out a half inch thick pane of glass from a vacant 9-story building. The glass landed on a parked car below. West winds gusting to 52 mph kicked up some blowing dust at Stapleton International Airport.

In 1996…lightning sparked a small fire near buffalo creek in southern Jefferson County. Only one acre burned before the fire was contained.

In 2002…heavy thunderstorm rain washed out a frontage road 6 miles north of Larkspur. The nearby mountain ranch subdivision was also flooded. Heavy rainfall in the Hayman fire burn area washed out a secondary road when debris from the runoff blocked a culvert. Hail as large as 3/4 inch fell near Keenesburg…in Castle Rock…and 7 miles to the south of Castle Rock.

In 2005…severe thunderstorms produced high winds. Wind gusts to 75 mph were measured near Longmont and to 60 mph just west of Boulder. No damage was reported.

In 2007…severe thunderstorms produced large hail in the foothills and suburbs west of Denver. Large hail from 1 to 2 inches in diameter was reported in the vicinity of Idaho Springs…Rollins and Edgewater.

In 2009…severe thunderstorms produced large hail and north and east of Denver. Hail up to one inch in diameter was observed near Erie and firestone. Hail up to 1 3/4 inches was observed 5 to 6 miles west-southwest of Byers. The golfball size hail caused extensive damage to a wheat field. In Aurora…six children received minor injuries when lightning struck a nearby tree. The injuries occurred when they were knocked down by the blast. None of the children suffered burns or appeared to have been directly hit by lightning.

Continue reading July 3 to July 9 – This Week in Denver Weather History →

Our look back at this week in Denver weather history certainly has plenty of the usual suspects related to severe weather. Most notable however are the many occurrences of lightning strikes and the effects they can have from sparking fires to causing significant injury and death.

From the National Weather Service:

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In 1969…high winds raked Boulder causing one fatality and some injuries. One man was injured by a falling tree limb. At the National Center for Atmospheric Research in Boulder… Sustained winds of 55 to 60 mph with wind gusts to 123 mph were recorded. In downtown Boulder…winds averaged 30 to 40 mph with gusts to 70 mph. Widespread minor damage occurred… Especially in the Table Mesa area of south Boulder. Much tree damage occurred in the older areas of Boulder where several trees were uprooted. A mobile home was overturned by the winds. At Stapleton Airport…west winds gusted to 43 mph on the 25th and 37 mph on the 26th.

In 1975…strong winds damaged utility lines…buildings… vehicles…trees…and power lines in Boulder and other communities to the north of Boulder. Microburst winds gusted to 45 mph at Stapleton International Airport on the 25th.

In 1983…heavy rain fell in the foothills west of Denver with 1.50 inches in 30 minutes at Intercanyon. Heavy rain continued over metro Denver on the 26th with two-day storm totals at many locations ranging from 1.00 to 2.50 inches. Rainfall totaled 1.37 inches at Stapleton International Airport on the 26th.

In 1985…one to two inches of rain fell over metro Denver. At Stapleton International Airport…rainfall totaled 0.93 inches…thunderstorm winds gusted to 44 mph…and 7/10 inch hail was measured. The air mass was unusually cold for the season…and snow fell in the foothills above 8 thousand feet. The high temperature of only 63 degrees on the 26th equaled the record low maximum reading for the date.

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In 1873…there was a great deal of smoke from a large forest fire in the mountains to the southwest of the city and a smaller fire directly to the west.

In 1874…fires at timberline to the west were visible from the city. New and extensive fires were continually started from south to northwest along the ridge line. Carelessness of tourists was the apparent cause of the fires. Large and valuable tracts of timber had already been destroyed.

In 1890…the only thunderstorm of the month produced a trace of rain. A trace of rain also fell on 7 other days. This was the only precipitation recorded during the month… Making it the driest June on record.

In 1893…northwest winds were sustained to 45 mph with gusts to 48 mph.

In 1971…a microburst wind gust to 58 mph was recorded at Stapleton International Airport. Dust devils were sighted.

In 1980…strong gusty thunderstorm winds damaged several mobile homes in Thornton. Thunderstorm winds gusted to 37 mph at Stapleton International Airport.

In 1986…hail piled up 1 1/2 inches deep in Golden Gate Canyon and covered roadways an inch deep in Evergreen.

In 1988…a tornado touched down 2 miles north of Watkins. It was on the ground for 15 minutes and did no reported damage.

In 1989…two inch diameter hail fell at Kassler…1 inch hail at Louviers…and 1 1/2 inch hail at tiny town.

In 1991…high winds…not associated with thunderstorms… Damaged a home in the Green Mountain area. The strong winds picked up a heavy metal and glass table on the deck of a house and threw it into the house. The table was destroyed and the house received considerable damage.

In 1992…3/4 inch diameter hail fell in south Aurora and near Buckley Air National Guard base. Golf ball size hail was reported in Parker.

In 1994…the all-time highest recorded temperature in June and the second highest temperature ever recorded in Denver… 104 degrees occurred. This was the hottest day in Denver since August 8…1878…when the temperature reached 105 degrees.

In 2005…strong thunderstorm winds gusting to 58 mph damaged a garage and some nearby trees near Fort Lupton. Winds also gusted to 58 mph near Watkins. Thunderstorm winds gusted to 60 mph near Roggen. Hail to 3/4 inch in diameter was measured in southwest Aurora.

In 2009…severe thunderstorms moving through Denver and the surrounding metro area produced intense thunderstorm winds. At Denver International Airport…a wind gust blew a luggage car into a southwest airlines airplane causing some damage. Peak wind gusts included: 68 mph at Denver International Airport…4 miles west of rocky mountain metropolitan airport and 12.5 miles north of Lowry AFB; 64 mph near Arvada and Parker; and 60 mph in Aurora/cherry.

Continue reading June 26 to July 2 – This Week in Denver Weather History →

Heavy rain, flooding, lightning, tornadoes and hail are not at all uncommon this time of year and we see plenty of those types of events in our look back at this week in Denver weather history. Probably one of the most notable events occurred 10 years ago when a thunderstorms with large hail ripped through Denver International Airport causing $10 million in property damage and damaged dozens of airplanes.

From the National Weather Service:

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In 1874…during the afternoon… Large columns of smoke from extensive fires in the mountain forests moved over the city from the west and southwest.

In 1875…while no precipitation was measured in the city… Rainfall over the palmer divide caused Cherry Creek to rise to the highest level in 10 years.

In 1977…hail up to 2 inch diameter damaged two patrol cars in Castle Rock.

In 1983 golf ball size hail fell just north of Bennett.

In 1990…lightning from a thunderstorm struck the roof of a house in south Boulder. Residents of the house were able to extinguish the ensuing fire with a garden hose…but not before several shingles had burned.

In 1992…thunderstorms produced hail up to 2 inches in diameter in central Douglas County near Castle Rock. Hail was 3 inches deep on I-25 south of Castle Rock. A funnel cloud was sighted near Parker.

In 1997…a 66-year-old man was knocked unconscious by a bolt of lightning while he was golfing at the eagle country club in Broomfield.

In 2000…dry microburst winds gusting to near 70 mph were reported across southeast Boulder and northern Jefferson counties. Peak wind gusts included: 68 mph at the national wind technology center…67 mph at Jefferson County airport… And 65 mph in Broomfield.

In 2001…severe thunderstorms produced large hail in the foothills southwest of Denver. Hail as large as 1 3/4 inch in diameter fell near conifer and Bailey.

In 2002…lightning damaged the Evergreen fire protection district radio repeater. One microwave transmitter…the main fire channel transmitter…and two solar panel controllers were destroyed. Lightning struck a garage and caused a small fire. Two vehicles parked in the garage were damaged. Hail to 3/4 inch in diameter fell near Castle Rock.

In 2004…severe thunderstorms produced hail to 3/4 inch in diameter near Castle Rock…Larkspur… And Golden.

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In 1875…smoke from several large forest fires in the mountains was visible from the city on each of these days.

Continue reading June 19 to June 25 – This Week in Denver Weather History →

The first half of June is when Colorado’s severe weather season really kicks into high gear and our look back at this week in Denver weather history reflects that. Numerous flooding, hail, and tornadic events punctuate just how dangerous and damaging our weather can be this time of year.

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In 1999…damage from several hailstorms in and near metro Denver totaled 35 million dollars. About 17.5 million dollars was from automobile claims with another 17.5 million in homeowner claims. The areas hardest hit by the storms included Castle Rock…Commerce City…Evergreen… And Golden.

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In 1901…south winds were sustained to 45 mph with an extreme velocity to 47 mph.

In 1917…northwest winds were sustained to 40 mph with gusts to 45 mph.

In 1927…flooding on Little Dry Creek in Englewood resulted in two deaths.

In 1947…a trace of snow fell over downtown Denver during the early morning. This was the latest last snow of the season (trace or more). This also marked the end of the longest snow season…264 days…from the first snow…a trace…on September 22…1946. High temperature of 43 degrees was a record low maximum for the date. Minimum temperature of 33 degrees was a record low for the date.

In 1971…a funnel cloud sighted over Arvada possibly touched down at the base of the foothills. The public reported 3/4 inch to 1 inch diameter hail over the city of Denver.

In 1974…strong thunderstorm winds caused damage to power lines in metro Denver. Northwest winds gusted to 45 mph at Stapleton International Airport.

In 1975…a thunderstorm wind gust to 56 mph was recorded at Stapleton International Airport.

In 1982…three small tornadoes were sighted near Bennett. One of the twisters caused minor crop and road damage along its path. A brief tornado was sighted by national weather service observers at Stapleton International Airport.

In 1983…3/4 inch hail fell in Boulder. Golf ball to 3/4 inch size hail fell in Arvada…denting cars and house roofs. Over a thousand hail damage insurance claims were filed from the area. Golf ball size hail also fell in Northglenn and Bennett…1 to 2 inch hail in Thornton…2 1/2 inch hail in northeast of Denver. A tornado was sighted 10 miles northeast of Stapleton International Airport; it was only on the ground for 1 to 2 minutes.

In 1984…large hail pelted many parts of southern metro Denver. Fifteen aircraft were damaged by golf ball size hail at Centennial airport. Golf ball size hail was reported in south Denver…and 3/4 inch hail was measured in southeast Aurora.

In 1987…a small weak tornado touched down for about 3 minutes near the intersection of I-70 and Colorado Blvd in northeast Denver. No damage was recorded. A microburst wind gust to 53 mph was recorded at Stapleton International Airport.

In 1991…in the city of Denver…lightning struck a tree under which seven people were picnicking. One person was critically injured. The others received only minor injuries.

In 1992…golf ball size hail fell in Evergreen.

In 1994…microburst winds gusting to 53 mph kicked up some blowing dust at Stapleton International Airport.

In 1996…lightning struck a house in Parker…which sparked a fire. The bolt was strong enough to blow nails out of the drywall in one room. About 85 percent of the house was damaged. No dollar estimate of the damage was available. Lightning also struck a power line in Boulder…which left 250 customers without electricity for a short time.

In 1997…a tornado touched down near Parker…damaging some construction equipment. Hail to 2 inches in diameter was measured in Henderson. One inch diameter hail fell in the city of Denver with 3/4 inch hail measured in Lakewood.

In 1999…hail as large as 1 1/2 inches in diameter struck Hudson. A funnel cloud was sighted by ramp personnel to the east of Denver International Airport.

In 2003…lightning blew a hole in the roof of a house in Highlands Ranch. The bolt knocked several holes in the bedroom ceiling and damaged the home’s electrical system.

In 2004…lightning struck a home in Louisville…but caused only minor damage.

In 2006…a strong microburst wind gust…estimated at 69 mph… Ripped the roof off a horse barn near the intersection of Havana Street and Smith Road in Denver. A 13 year old girl was injured…when she was thrown from a horse inside the barn at the time the roof was being torn off. A thunderstorm produced a microburst wind gust to 54 mph and a trace of rainfall at Denver International Airport. A severe thunderstorm produced hail to 0.75 inch near Watkins.

Continue reading June 12 to June 18 – This Week in Denver Weather History →

The first part of June typically brings some of Denver’s most eventful weather of the year and we clearly see that in our look back at this week in Denver weather history. From many damaging hail and wind events to heavy rains that resulted in flooding and even the Southlands Mall tornado of 2009 it has been an eventful week in history.

From the National Weather Service:

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In 1921…heavy rainfall for nearly a week…on top of streams already swollen by mountain snowmelt…produced widespread flooding over the South Platte River basin…including the tributaries through the canyons to the west and southwest of Denver. Heavy rainfall over the 6-day period totaled 3.36 inches in Boulder…4.98 inches in Morrison…4.27 inches in Castle Rock…and 2.94 inches in the city of Denver. Rainfall amounts in the foothills were estimated between 3 and 6 inches. The narrow-gage tracks of the Colorado and southern railroad were destroyed in the Platte Canyon. From the mouth of the canyon through the city to near Brighton… The river spread from 1/2 to nearly 1 1/2 miles wide… Flooding farm and pasture land and destroying or damaging many bridges. In the city…many businesses along with as many as 500 homes were inundated…forcing their evacuation. Bridges were swept away. The high waters flooded the rail yards and stock yards in lower downtown…closing three adjacent packing houses. The heavy rains also caused flooding on Boulder creek in Boulder on the 6th.

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In 1965…lightning and an 18-hour rain storm damaged streets and roads and telephone and power lines across metro Denver. Precipitation totaled 2.77 inches at Stapleton International Airport where the visibility was reduced to 3 miles at times from pre-frontal thunderstorms and heavy upslope rains.

In 1998…a late season snow storm struck the Front Range foothills. Up to 5 inches of snow fell in Coal Creek Canyon. Light snow also fell over western sections of metro Denver and briefly at Denver International Airport. Snow covered the grass at the Denver federal center in Lakewood before melting around mid-morning on the 5th. No snow fell at the site of the former Stapleton International Airport. Several temperature records were set. High temperatures of 47 degrees on the 4th and 49 degrees on the 5th were record low maximums for their respective dates. Minimum temperature of 34 degrees on both the 5th and 6th were record lows for those dates.

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In 1864…high water on the west fork of clear creek caused a small dam near empire to fail…which destroyed several downstream bridges.

In 1885…a windstorm during the afternoon and early evening produced south to southwest winds at sustained speeds up to 42 mph.

In 1937…a trace of snow fell in downtown Denver. This was the latest snowfall of record at the time. Light rain and snow were mixed around mid-day. Precipitation totaled only 0.01 inch. North winds were sustained to 20 mph.

In 1941…hail of unknown size fell on the city.

In 1961…lightning struck and injured an airman outside a base classroom at Lowry Air Force Base. Funnel clouds were sighted near Frederick and firestone north of Denver. The one near Frederick briefly touched down in an open field but caused no damage. Heavy rain and hail hit the Fort Lupton area causing damage to crops. Heavy rain in Frederick added to the flood damage of the 3rd. A pilot reported a funnel cloud that touched down briefly and then dissipated south of Castle Rock.

In 1965…a lightning-caused fire destroyed a mountain home near Rollinsville.

In 1988…a tornado touched down 5 miles east of Lafayette near I-25 and stayed on the ground for 15 minutes. The twister hit a campground…demolishing one trailer and damaging six others…along with 4 cars. The rope-like funnel also blew down fences…signs…and electrical boxes. The twister moved a 1500-pound hay wagon 150 feet. Total damage to the campground was estimated at 50 thousand dollars. Another tornado touched down between Broomfield and Lafayette…staying on the ground for about 20 minutes. The twister hit a subdivision…unroofing one abandoned house and causing minor damage to a dozen others. A four- car garage and three barns were destroyed. At one location a chain link fence…a satellite dish…and a shed were destroyed…while the deck and garage of the house were damaged. A grain storage tank was moved 200 feet. There were reports of boards being blown through walls; one came through a kitchen.

In 1992…lightning struck a 15-year-old boy…causing minor injuries…in Adams County 6 miles north-northeast of Stapleton International Airport. Thunderstorm winds gusted to 63 mph at Jefferson County Airport near Broomfield…to 58 mph at the U.S. Atomic Energy Commission’s facility at Rocky Flats…to 58 mph in Thornton…and to 48 mph at Stapleton International Airport where 1/8 inch diameter hail fell.

In 1996…strong microburst winds up to 60 mph damaged several trees in Boulder…snapping large branches 1 to 2 inches in diameter.

In 1997…a woman was struck by lightning as she was walking to her car in Nederland. The lightning bolt apparently struck a nearby power line and arced into her left hand. She received minor injuries.

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In 1977…lightning caused several power outages and moderate damage to a railroad building.

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In 1954…thunderstorm winds at speeds of 50 mph with gusts as high as 59 mph briefly reduced the visibility to 1 mile in blowing dust at Stapleton Airport.

In 1967…the public reported golf ball to 1 3/4 inch diameter hail in the city…3 miles west-southwest of Stapleton International Airport. The amount of damage was unknown. Thunderstorm winds gusted to 46 mph at Stapleton International Airport.

In 1981…hail to 3/4 inch in diameter was reported in east Denver.

In 1990…golf ball size hail was reported near Strasburg on I-70 east of Denver.

In 1991…a tornado was spotted by national weather service personnel and weather spotters…14 to 17 miles northeast of Stapleton International Airport. A funnel cloud was sighted over south Aurora just east of Buckley Field…and a tornado was spotted just east of Watkins. No damage was reported. Thunderstorms moved through Aurora and dropped hail up to 1 inch in diameter. The storms also produced heavy rain… Up to 1 inch in 30 minutes…causing flooding of streets. Water was reported hood deep…stranding motorists. Water covered fire hydrants at some intersections.

In 1995…a waterspout sighted over Standley Lake in northern Jefferson County…quickly dissipated once it reached shore. A brief tornado…which was momentarily visible by a dust debris cloud on the ground…damaged the roof of a house in Westminster. A funnel cloud was sighted just south of Lafayette. Hail from 3/4 to 1 1/4 inches in diameter fell over north Boulder. Thunderstorm outflow produced north wind gusts to 44 mph at Denver International Airport.

In 1997…a tornado touched down near baseline reservoir just east of Boulder. The tornado struck a home…tearing off part of the roof. A storage building nearby was nearly leveled and 5 trees were uprooted. The twister then moved onto baseline reservoir…forming a huge waterspout. Several recreational vehicles and a boat dock were also damaged. A nearly stationary line of thunderstorms dumped 4.60 inches of rain on portions of Thornton. Extensive flooding of streets and underpasses and other low lying areas was reported. Several businesses were flooded and basements in the area were damaged. Rainfall totaled 1.02 inches at Denver International Airport and 1.24 inches at the site of the former Stapleton International Airport. Large hail…up to 1 3/4 inches in diameter…fell over the city of Denver with 3/4 inch hail measured in Littleton and near Henderson.

In 1999…high winds developed for a brief time in and near the foothills of Boulder. The Gamow Tower on the University of Colorado campus recorded a wind gust to 87 mph. Winds peaked to 71 mph atop Niwot Ridge near the continental divide west of Boulder.

In 2003…a small tornado touched down near Strasburg…but did no damage.

Continue reading June 5 to June 11 – This Week in Denver Weather History →

There are many notable events on our look back at the weather history books for this week but one in particular stands out. It was 30 years ago this week, on June 3, that the infamous Thornton tornado struck. This twister still stands as the most damaging tornado to have ever struck the Denver metro area.

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In 1995…a cool period with light morning showers and moderate to heavy afternoon showers and thunderstorms pushed rivers already swollen from mountain snow melt over their banks causing minor flooding. Streams and rivers such as the South Platte and Boulder creek flooded meadowlands…bike paths…roads near streams…and other low lying areas. No significant property damage was reported and crop damage was unknown. Rainfall totaled 1.79 inches at the site of the former Stapleton International Airport and only 1.51 inches at Denver International Airport.

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In 1934…the low temperature dipped to only 66 degrees…the all-time record highest minimum temperature for the month of May.

In 1958…a microburst caused a brief wind gust to 56 mph at Stapleton Airport.

In 1964…heavy rain caused flooding in the Harvey Gulch area of southeast Denver. The high water damaged homes… Businesses…streets…and bridges. At Stapleton International Airport…1.33 inches of rain were measured with 1.76 inches total rainfall on the 29th and 30th. The heavy rain during the last week of the month was the first significant precipitation since April 3rd.

In 1967…3/4 to 1 inch diameter hail stones fell in the city of Denver…but caused no reported damage. Hail as large as 3/4 inch was measured at Stapleton International Airport.

In 1975…the heaviest last snowfall of the season occurred when 5.6 inches of snow were measured at Stapleton International Airport. Rain all day on the 28th changed to snow on the 29th and accumulated to a depth of 4 inches on the ground. Northwest winds gusted to 31 mph. Precipitation (rain and melted snow) on the 28th and 29th totaled 1.48 inches.

In 1982…one man was killed and two others injured by a lightning strike as they stood under a tree in the city of Denver’s Washington Park.

In 1987…7/8 inch diameter hail fell near Castle Rock.

In 1990…thunderstorms over metro Denver produced several small funnel clouds and two small tornadoes. The first tornado (f0) touched down in northwest Denver and caused roof damage to a house and snapped off the tops of several trees. A second tornado (f1) touched down in Northglenn and moved into Thornton damaging a group of self storage garages…several vehicles…a wooden fence…several trees… And the roof of an auto parts store. No injuries were reported. The storms also caused minor street flooding across northern and western sections of metro Denver. Rainfall totals ranged from 1 to 3 inches. Lightning started a small fire at a home in northwest Denver. The fire was confined to the front rooms and was quickly extinguished. Snow plows were used to clear 2 to 4 inches of pea to marble size hail from a stretch of U.S. Highway 285 in Turkey Creek Canyon. Lightning felled a tree in northeast Denver…while strong winds snapped off several large tree limbs in the same area. Thunderstorm rainfall totaled 0.82 inch at Stapleton International Airport where southwest winds gusted to 30 mph.

In 1991…lightning struck a 13 year old boy in a field in Fort Lupton. The boy was in critical condition in an area hospital for 2 days before recovering.

In 1995…lightning struck a soccer goal post and injured 6 adults viewing a soccer game in Arvada. Although no one received a direct hit from the lightning…all escaped with only minor injuries…except one woman who was hospitalized.

In 1996…large hail…3/4 to 1 1/2 inches in diameter… Struck Lakewood and west Denver. Lightning sparked a small fire when it struck an oil storage tank 5 miles west of Brighton.

In 2001…lightning sparked a fire in an apartment complex in Aurora…forcing the evacuation of 24 units. Most of the fire damage was confined to the attic. Damage was estimated at 100 thousand dollars.

In 2004…a man and his son were struck by lightning while practicing on the driving range at the Meadows Golf Club in southwest metro Denver. The father was killed by the bolt…and his 16 year old son seriously injured. Three other people standing nearby received only minor injuries.

In 2010…hail up to 7/8 inch in diameter was reported in Broomfield.

Continue reading May 29 to June 4 – This Week in Denver Weather History →

If history is a teacher, our look back at this week in Denver weather history should provide great instruction on the dangers severe weather presents in our history. It was three years ago this week that the infamous Windsor tornado tore through the area killing one man and damaging hundreds of homes.

From the National Weather Service:

20-22

In 1959…a three-day rain caused some flooding in metro Denver where rain totaled 1.68 inches at Stapleton Airport. Showers…accompanied by hail near Brighton…caused some damage to truck crops. Heavy snow in the foothills caused damage to power and telephone lines.

20-27

In 2002…lightning sparked a wildfire near Deckers. Extremely dry conditions and very strong winds the following day allowed the fire…known as the schoonover…to consume 3850 acres before it could be contained. Thirteen structures were destroyed…including 4 homes…resulting in 2.2 million dollars in damage.

21-22

In 1878…overnight heavy rains of cloudburst intensity on the Palmer Divide to the south of the city caused flash flooding on Cherry Creek in Denver…which resulted in 2 deaths. A wall of water swept through the city between 2:00 am and 3:00 am on the morning of the 22nd. The flood was so sudden and unexpected that homes along the creek in the city were submerged in water knee deep before the slumbering occupants knew anything about it. By daybreak the banks on both sides of the creek were lined by residents viewing the destruction caused by the raging waters in such a short time. Seven bridges across the creek were destroyed in the city. Damage to private and city property was estimated between 30 and 50 thousand dollars. Quite a number of cattle and sheep were killed along the reach of the creek. Only 0.01 inch of rain fell in the city on the 21st with a trace of rain on the 22nd. Flash flooding also occurred on Kiowa Creek near Bennett on the night of the 21st when the flood waters washed out the Kansas Pacific Railroad bridge. An east bound freight train plunged into the turbulent waters killing the three crewmen. The locomotive was completely buried in the sand and never found to this day!

21-23

In 1876…snow changed to heavy rain over the city…resulting in widespread flooding along Cherry Creek and the South Platte River…nearly as great as the flash flood of May 19-20…1864. However…damage was greater because the city had grown much larger and there were more bridges for the flood waters to destroy. Precipitation in the city totaled 6.70 inches from 10:00 pm on the 21st through 3:00 am on the 23rd. The greatest precipitation ever recorded in Denver in 24 hours…6.53 inches…occurred on the 21st and 22nd. Small buildings and bridges along Cherry Creek were washed away by the flood waters. Bridges over the South Platte River were damaged. The city irrigation ditch was damaged and rendered unfit for service. Strong winds at speeds of 30 to 40 mph drove the heavy rain through brick walls 12 to 16 inches thick. Many sheep and cattle were either killed by lightning or drowned…including some 100 head of cattle in Jefferson County alone. There was immense damage to railroad tracks…especially the Kansas Pacific line to the east of the city. The Colorado central suffered estimated damage of 10 to 15 thousand dollars. In addition…the heavy rain caused extensive flooding on soda and bear creeks in the foothills. Flooding along Boulder creek inundated farm and pasture land in the Boulder valley and damaged a few bridges. Rail travel had to be suspended in the area for several days.

Continue reading May 22 to May 28 – This Week in Denver Weather History →