Thornton, Colorado, USA
UpdatedSat, 25-Sep-2021 7:15am MDT 


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August 15 to August 21: This week in Denver weather history

Sunday, August 15th, 2021 5:15am MDT

This Week in Denver Weather History

While not as common this time of year, severe weather can still strike as we close out summer.  Most notable are the heavy rain events that can come along as a result of the monsoon season.  The dangers of these are oftentimes ignored and as we see can oftentimes turn deadly.


In 1899…a thunderstorm produced southwest sustained winds to 43 mph with gusts to 46 mph.

In 1972…a pilot reported a funnel cloud briefly touching the ground in open fields…17 miles east-northeast of Stapleton International Airport.

In 1980…thunderstorm winds gusted to 55 mph in Boulder.

In 1982…brief heavy rain and winds estimated as high as 70 mph occurred in the conifer-Evergreen area.  No damage was reported.

In 1990…lightning triggered a small attic fire in a house near Sedalia…20 miles south of Denver.  A furious lightning storm caused widespread power outages across southern sections of metro Denver.  One lightning bolt knocked out an electrical substation…causing a 90-minute blackout in southeast Denver affecting nearly 10 thousand homes and businesses.

In 2007…severe thunderstorms produced large hail…up to 2 inches in diameter…near Larkspur.   Extensive damage to vehicles in the area was reported.  In Parker…lightning struck a residence.  The ensuing fire damaged the attic and top floor; causing $100000 in property damage.

In 2008…at least three homes were hit by lightning during the early morning hours in Arapahoe County.  Lightning also struck two homes in Castle Rock…damaging the roofs.

In 2013…a dry microburst uprooted 30 to 40 large trees across a 12-block area of the Park Hill neighborhood in east central Denver. Several trees were snapped near the base along with numerous branches…8 to 10 inches in diameter. Power poles and lines were also downed with resulted in outages which affected seven hundred residents. One of the downed trees crushed a car`s hood… narrowly missing the driver. At Denver International Airport…a peak wind gust of 22 mph was observed from the southwest.


In 1902…a thunderstorm produced west winds sustained to 48 mph with gusts to 60 mph…but only a trace of rain.

In 1952…a thunderstorm wind gust to 50 mph was recorded at Stapleton Airport.

In 1960…lightning struck a warehouse in central Denver… Causing 8 thousand dollars in damage to the building and stored electrical equipment.

In 1975…large hail…1 1/2 to 1 3/4 inches in diameter…fell about 4 miles north of Castle Rock.  Hail caused some minor damage in Aurora.  A funnel cloud was reported 25 miles east of Denver near Bennett.

In 1981…a tornado touched down briefly in open country just to the east of Aurora.  No damage was reported.

In 1982…a thunderstorm wind gust to 61 mph was recorded at Buckley Field in Aurora.  At the same time almost an inch of rain flooded and closed streets in south Aurora.  A woman was hit by lightning just north of Denver.  A house in the area was also struck.

In 1985…a thunderstorm produced strong wind gusts over southern metro Denver.  One strong wind gust hit Cheery Creek Reservoir…capsizing a boat and drowning a man.  The wind gusts…clocked as high as 50 mph…also downed a few trees.

In 1989…1 3/4 inch diameter hail fell at Intercanyon in the foothills of Jefferson County.

In 1990…lightning caused minor damage to a south Aurora home.  No injuries were reported.

In 1994…strong thunderstorm winds caused damage in southern Weld County near Hudson and Fort Lupton.  Two mobile homes were destroyed and a few lost their roofs.  Up to 20 downed power poles and the destruction of two 115 thousand-volt towers caused widespread power outages.  Thunderstorm gust front winds from the north gusted to 48 mph at Stapleton International Airport.

In 2000…lightning ripped most of the roof from a home in southeast Aurora.  The bolt sparked a fire which destroyed the residence.  Damage was estimated at 250 thousand dollars.

In 2002…the temperature climbed to a maximum of 100 degrees setting a new record high for the date.

In 2003…a teenager was injured when he was struck by lightning while camping at Herman Lake…13 miles northwest of Georgetown.  The boy was knocked unconscious and suffered minor injuries.


In 1979…heavy thunderstorm rains on each of 4 consecutive days dumped a total of 2.62 inches of rain on Stapleton International Airport.  The heaviest rain…1.05 inches… On the 19th was accompanied by 1/4 inch diameter hail.

» Click here to read the rest of August 15 to August 21: This week in Denver weather history

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Thornton’s weekend weather to offer up temps near normal, some chances for storms

Friday, August 13th, 2021 4:50am MDT

Largely “normal” weather for this time of year on tap for the weekend. Temps will be close to average and each day has at least a bit of a chance for thunderstorms.

For Friday, mostly sunny skies will be with us as temperatures reach the upper 80s. Some PM thunderstorms will be possible, mainly after 3:00pm. Tonight, any storm activity will be largely done by 9:00pm or so. Skies will then be mostly clear and overnight lows will drop to around 60 degrees.

Saturday offers up lots of sun for the majority of the day. Highs will top out around the 90 degree mark with just the slightest chance for a PM storm. Saturday night into Sunday morning, partly clear skies will be above. Overnight lows again drop to around 60 degrees.

Sunday sees more of the same as the previous two days. Highs will again be near 90 degrees under mostly sunny skies. The afternoon brings some isolated thunderstorm activity.

Have a great weekend!

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Thursday brings a bit of a cool down, offers just a slight chance for storms

Thursday, August 12th, 2021 4:53am MDT

The change won’t be huge but we do at least see a break from the recent hot weather today. A cold front will be moving in this morning and that will bring temps close to near normal and may help generate a thunderstorm or two.

Sunny skies start us off then we will see a few clouds by mid to late morning. Smoke will still be present but should ease a good bit. Highs today will top out right near the average high for the date of 88 degrees.

Some scattered thunderstorms will be seen after noon and into the evening. Right now, unfortunately, most activity looks like it will be south of us but we can’t entirely rule out us seeing some action.

Tonight, skies will be partly clear with overnight lows around 60 degrees.

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August 8 to August 14: This week in Denver weather history

Wednesday, August 11th, 2021 2:44pm MDT

This Week in Denver Weather History

Monsoon season in Colorado typically brings short-lived but heavy rains.  These can result in flash flooding and we see that in our look back at this week in Denver weather history.  Also notable are the number of lightning deaths and injuries as well as hail events and even a swarm of grasshoppers!


In 1874…swarms of grasshoppers invaded the city.  Millions of them were seen cruising through the air.  The insects were apparently picked up by a thunderstorm gust front and carried into the city.  The grasshoppers had ravaged crops in surrounding counties for the last month.

In 1878…the highest temperature ever recorded in Denver…105 degrees…occurred at 3:20 pm.  This temperature was equaled on July 20th in 2005.

In 1969…the temperature reached 100 degrees at Stapleton International Airport.

In 1976…in Thornton…a 13 year old boy riding a bicycle was struck and killed by lightning.

In 2000…lightning struck three homes in central Arapahoe County east of Denver.  Damage was estimated at 47 thousand dollars.

In 2003…hail to 1 inch in diameter pelted Denver.  Hail to 7/8 inch was measured in Boulder.

In 2008…heavy rain also caused flash flooding over south Denver and its nearby suburbs. Heavy rain…from 2.5 to 4 inches…fell in less than 90 minutes.  Firefighters rescued 20 people as the water quickly rose along creeks…flooded roadways…and stranded motorists.  Three people had to be rescued along Cherry Creek when the bike path flooded.  In Evergreen…a man suffered minor injuries when he was struck by lightning.  It entered his finger…traveled down his body… And exited his foot.


In 1979…heavy thunderstorm rains on each of three consecutive days dumped a total of 2.22 inches of rain at Stapleton International Airport.  The heaviest rain… 0.95 inches…fell on the 9th.  Small hail to 1/8 inch diameter fell on the 8th.


In 1875…clouds of grasshoppers were seen flying through the air on the prevailing winds during each day.


In 1900…a thunderstorm produced west winds sustained to 47 mph with gusts to 55 mph…but only 0.01 inch of rain.

In 1902…a thunderstorm produced no rain and north winds sustained to 52 mph with gusts to 60 mph.

In 1934…heavy cloudbursts in the foothills near Kittredge and at the head of Mount Vernon Creek caused flash flooding on both Bear Creek and Mount Vernon Creek at Morrison… Which resulted in 6 deaths and much property damage. The highway in Mount Vernon Canyon was destroyed by the flood waters.

In 1981…3/4 inch hail fell at Kittredge near Evergreen in Jefferson County.

In 1987…3/4 inch hail fell in Boulder and 9 miles northwest of Castle Rock.

In 1995…lightning struck a 16-year-old counselor in the back of the head while he and a friend were standing under a tree at the singing river ranch…7 miles west of Evergreen.  He stopped breathing…but his friend was able to summon help and they were able to revive him.  He was hospitalized for a few days and released.

In 1998…brief…weak tornadoes (f0) were sighted near Bennett and Roggen.  No damage was reported.  Hail as large as 1 inch diameter fell in Franktown with 3/4 inch diameter hail measured near Castle Rock. Thunderstorm winds gusted to 61 mph near Roggen.


In 2006…mid and high cloudiness overnight on both days resulted in two temperature records.  The low temperature of 71 degrees on the 9th was a record high minimum for the date.  The low temperature of 68 degrees on the 10th equaled the record high minimum for the date first set in 1936.


In 1924…0.01 inch of rain fell over downtown Denver.  This along with the 0.01 inch of rainfall on the 4th was the only rainfall of the month…making this the driest August on record in the city.

In 1962…the high temperature reached 100 degrees at Stapleton Airport.

In 1970…hail stones to 1 inch in diameter were reported in the Fort Lupton  area.

In 1972…dry thunderstorm microburst winds gusting to 46 mph briefly reduced the surface visibility to 3/4 mile in blowing dust at Stapleton International Airport.

In 1978…lightning struck two men in Aurora…killing one and injuring the other.

In 1982…a tornado was sighted near Castle Rock and remained on the ground for 10 minutes.  Wind gusts to 60 mph were reported in Castle Rock.  No damage was reported.

In 1994…heavy thunderstorm rains caused flash flooding on Lena Gulch in west metro Denver.  Damage was estimated at 50 thousand dollars.  Lightning struck a house in Westminster…causing a small attic fire.

In 1996…strong thunderstorm winds toppled a tent at a company picnic in Westminster.  Five people received minor injuries when the tent collapsed.  Two cars nearby were also damaged by flying debris.  A weak tornado (f0)…first sighted near Denver International Airport…traveled east to near Bennett and Strasburg.  No significant damage was reported.

In 1998…heavy rain caused flooding and flash flooding problems over southwest metro Denver.  An observer in Lakewood measured 3.26 inches of rainfall in an hour. Several streets were flooded in central Lakewood.  In addition…a trailer park along Lena Gulch in Wheat Ridge was evacuated due to high waters.  One inch diameter hail fell near Roggen.

In 1999…thunderstorm-producing tornadoes…damaging straight line winds…heavy rain…and hail hammered metro Denver.  In the city…small hail and heavy rainfall…up to 2.50 inches an hour…caused a 20-foot by 50-foot section of the roof to collapse at a furniture warehouse.  Damage to the warehouse was estimated at 1 million dollars.  Heavy rain also flooded several underpasses with up to 3 feet of water…which resulted in a number of stalled vehicles.  In Fort Lupton…a tornado bounced across the area.  Spotty damage was reported along a 5-mile path as trees…power poles…and lines were downed.  In addition…an empty semi-trailer was overturned onto another vehicle northeast of the town.  Thunderstorm winds gusted to 81 mph south of Fort Lupton.

In 2004…severe thunderstorms pummeled metro Denver with large hail.  Hail up to 3 inches in diameter was measured 10 miles east of Castle Rock.  Two inch diameter hail fell in Louisville…10 miles north of Hudson…and 1 mile east of Brighton.  Hail to 1.75 inches was reported in Englewood… 1 mile south of Ft. Lupton…and 8 miles east of Boulder. Hail to 1.50 inches was reported around Boulder…near Broomfield…and in Lafayette…Thornton and Greenwood Village. Hail from 3/4 to 1 inch in diameter was found in Broomfield… Brighton…Castle Rock…Denver and Thornton…and near Longmont… Northglenn…Greenwood Village…Morrison…and Wheat Ridge. Severe thunderstorm wind gusts were recorded to 66 mph in Parker and to 60 mph 5 miles northeast of Boulder.  There were no damage estimates from the hail or wind.


In 1872…fog was very dense until about 8:00 am.  There was water dripping from the roofs of houses as if it had rained. The rain gage showed 0.01 inch of moisture…even though there had been no rainfall.

In 1927…an apparent dry microburst produced only a trace of rain and brief northwest winds sustained to 34 mph with gusts to 44 mph.

In 1980…hail up to golf ball size caused some roof and car damage in the southern part of Aurora.

In 1990…lightning ignited a storage tank filled with 10 thousand gallons of crude oil in a farmer’s field near Dacono…25 miles north of Denver.  Flames shot to 40 feet high for nearly 2 hours before being extinguished.  A lightning bolt also struck 21 miles north of Denver at an Erie fire station…causing extensive damage to the gas meter and electrical system.  The sudden power surge blew out the station’s television set…a refrigerator…and a pop machine.  Small fires spread throughout the structure… Totally destroying the building’s electrical wiring.  The fires were quickly extinguished by the in-resident fire fighters.  Golf ball size hail was reported in Denver near the intersection of Santa Fe Drive and I-25.

In 1992…dime size hail fell in Westminster.

In 1994…strong thunderstorms produced large hail across northwest and north metro Denver.  One inch diameter hail fell in Brighton with 3/4 inch hail reported in Westminster and at Indian Hills in the foothills west of Denver. Lightning struck a house in Arvada.  The resulting fire destroyed one-third of the house.  Funnel clouds were sighted over Westminster.

In 1997…large hail…strong winds…and torrential rains hammered portions of Lakewood and south Denver.  Nearly 1 inch of rain fell in the span of 10 minutes in south Denver with a storm total of 1.81 inches.  Street flooding was extensive as gutters and other drainage systems in the area were clogged by hail…piled several inches deep…and other debris.  Strong thunderstorm winds to 50 mph and large hail accompanied by heavy rain caused extensive damage to cars…homes…and businesses.  Several trees were downed by the strong winds…and trees were stripped of their leaves by hail.  A water lily exhibition on display at the Denver Botanic Gardens was heavily damaged.  Final estimates of the damage included 60 million dollars to automobiles and an additional 68 million dollars to homes and businesses.  Hail to 1 1/2 inches in diameter fell in south Denver with 3/4 to 1 inch hail in Lakewood.  A man received minor injuries in Aurora when he was struck by lightning while talking on the telephone.

In 2003…hail to 3/4 inch in diameter was measured in Aurora near Cherry Creek.

In 2012…a severe thunderstorm produced a wind gust to 60 mph at Rocky Mountain Metropolitan Airport.

» Click here to read the rest of August 8 to August 14: This week in Denver weather history

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Thornton’s Wednesday continues the hot temperatures, smoky skies

Wednesday, August 11th, 2021 4:55am MDT

In their forecast discussion this morning, the National Weather Service said, “The forecast headline of “hot and dry” is starting to become as stale as the air across the Denver metro.”

Yeah, can’t argue with that one bit. If you recall the forecast from recent days, don’t bother to read this as you won’t see anything really different from then.

Sunny skies start us off today then mid to late afternoon a few clouds will arrive. Smoky / hazy conditions will be above throughout. High temperatures will be reaching the mid-90s, perhaps a bit warmer than that even.

Tonight, the smoke lingers with partly clear skies. Overnight lows will be on the low 60s.

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Another smoky, hot day for Thornton’s Tuesday

Tuesday, August 10th, 2021 5:00am MDT

Not much change in our weather forecast today versus what we experienced yesterday. Temperatures will cool a couple of degrees but remain above normal and smoke will again obscure those blue skies.

Sunny skies start us off and then we will see a few clouds as the day progresses. The smoke will once again be prevalent. High temperatures today will top out in the low to mid-90s. Conditions will remain dry.

Tonight, mostly clear skies will be above with areas of smoke. Overnight lows will dip to around 60 degrees.

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Monday starts the workweek with more of the same hot, smoky conditions

Monday, August 9th, 2021 4:59am MDT

If you’re looking for a change from the recent weather conditions, you won’t find it in this forecast. Temperatures are going to remain well above normal and the smoke will continue to impact the sky and air quality.

The day starts off with sunny, but hazy skies. Some cloud cover will be seen later in the day. Smoke will be a big part of the day with it increasing and peaking about mid-afternoon. Temperatures today will top out in the mid-90s.

Tonight, smoke will continue with partly clear skies. Overnight lows will dip to the low 60s.

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Thornton’s weekend weather to offer up two hot days with one cooler day in the middle

Friday, August 6th, 2021 4:57am MDT

The three-day period will be bookended with hot days. Between, Saturday will see things cool a bit with mercury readings closer to normal.

For Friday, we start out clear and then cloud cover will slowly be increasing. We will continue to experience hazy, smoky skies. Highs today will be heading toward the mid-90s. The afternoon brings a chance for a shower although most at this time look to be high-based and likely won’t amount to much if anything. Tonight, we will have some breezy winds in the evening but otherwise calm conditions. Lows will be around 60 degrees under mostly clear skies as a weak trough pushes in.

Saturday will be the coolest day of the weekend. Sunny to mostly sunny skies with smoke can be expected. Highs will be near the 90 degree mark. Saturday night into Sunday morning, lows will be in the upper 50s under mostly clear skies.

Sunday sees the heat return. Conditions will be calm and dry as we head toward a high of 95 degrees. Sunny skies will be with us the majority of the day. Have a great weekend!

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August 1 to August 7: This week in Denver weather history

Tuesday, August 3rd, 2021 3:37pm MDT

This Week in Denver Weather History

August isn’t normally associated with severe weather but our look back at the history books show it certainly can and does happen.  We see many occurrences of dangerous lightning and of particular note is the flood events – a byproduct of the monsoon season the first of August brings.


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.


In 1888…heavy rain in the mountains and foothills caused flooding on clear creek in Golden.  The high waters also washed away portions of the railroad tracks in the canyon between Idaho Springs and Golden.

In 1901…the temperature reached a high of 100 degrees in the city.

In 1902…the high temperature climbed to 100 degrees in downtown Denver.

In 1914…a thunderstorm produced 1.00 inch of rainfall in just 21 minutes and north winds sustained at 43 mph with gusts to 50 mph.  Rainfall totaled 1.17 inches.

In 1938…the temperature climbed to a high of 100 degrees in downtown Denver…which is the record maximum for the date.  The temperature was also recorded on this date in previous years.

In 1976…flight operations at Stapleton International Airport were suspended for 90 minutes when the airport tower radar was knocked out and water reached a foot deep on some taxi ramps after 1.50 inches of rain fell in one hour.  Heavy rain also caused minor flooding in east Denver and Aurora where lightning damaged the roof of a home and injured the owner.  One young man was swept down a flooded ditch…but was rescued by firemen.  A number of rafts were floated in flooded streets.  Thunderstorm rainfall totaled 1.71 inches at Stapleton International Airport.

In 1978…a tornado damaged a house and broke a power pole 5 miles northwest of Parker.  A microburst wind gust to 52 mph briefly reduced visibility to 1 mile in blowing dust at Stapleton International Airport.

In 1985…heavy thunderstorms roared through the southern and western sections of metro Denver…producing large hail and heavy rain.  Lightning hit a recreational vehicle trailer causing it to burn.  There was a lot of street flooding over western suburbs where rainfall totaled over 2 inches in some areas.  One inch diameter hail was reported in Littleton and near Evergreen.  Hail piled 4 to 6 inches deep at Tinytown in the foothills southwest of Denver.

In 1990…a small rope-like tornado was spotted in open country 15 miles southeast of centennial airport. No damage was reported from the twister.

In 1992…pilots reported a funnel cloud near the construction site of the new Denver International Airport.  A few minutes later…a tornado was reported near Bennett.  The tornado remained on the ground for about 18 minutes and was visible from the national weather service office at Stapleton International Airport.  Thunderstorm wind gusts to 70 mph were reported near Bennett and Watkins with a wind gust to 60 mph at Brighton.  Two men were injured when struck by lightning.  A young man sustained serious injuries when struck by lightning while jet skiing on Cheery Creek Reservoir.  A man received only minor injuries when struck by lightning while golfing in Westminster.

In 1994…heavy thunderstorm rains in the foothills west of Denver caused the closure of the Virginia Canyon Road north of Idaho Springs by rocks and debris.

In 2001…a 34 year old man on the South Platte River bike path in Denver received minor injuries when lightning struck a nearby tree.  Lightning…coupled with strong thunderstorm winds…knocked out electrical power to about 10 thousand homes and businesses in Golden.

In 2006…strong thunderstorms hit southern metro Denver. A severe thunderstorm wind gust estimated to 71 mph knocked down a tree in Aurora near Cherry Creek. Lightning sparked a fire in a home near Lone Tree and struck a transformer at an RTD light rail station at Interstate 25 and Yosemite street.  Heavy thunderstorm rainfall forced the closure of Arapahoe road between Holly and Quebec streets due to high water.  Flooding was also reported near park meadows mall and greenwood village.  Heavy rainfall also caused flooding in Highlands Ranch…Lone Tree…and Parker.  Water up to 6 inches deep was reportedly running over the roads.


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

In 1911…an apparent dry microburst produced sustained west winds to 42 mph.

In 1972…one workman was killed and another injured when a strong gust of wind destroyed a partially completed apartment building in south Denver.  Hail to 1 3/4 inch diameter fell in Golden.

In 1973…hail to 3/4 inch diameter was reported in Boulder.

In 1986…a major outbreak of severe thunderstorms occurred along the Front Range.  Thunderstorms developed explosively.  Some places were hit by large hail twice. Two inch diameter hail broke car windows on I-25 west of Brighton…and up to 1 1/4 inch hail broke windows in Thornton.  Baseball size hail damaged several planes near Watkins.  Funnel clouds were sighted around Aurora.  Hail over 1/2 inch in diameter covered the ground 3 to 4 inches deep at Hudson northeast of Denver.  Most of the hail fell north of metro Denver…but 3/4 inch diameter hail was measured at Stapleton International Airport.  Total damage from the hail storms this day was estimated at over 10 million dollars.

In 1991…late afternoon thunderstorms produced heavy rain across metro Denver.  Two feet of water covered parts of I-25 in southeast Denver…while one foot of water covered parts of U.S. Highway 285 in Englewood.  Thunderstorm rainfall totaled 0.50 inch at Stapleton International Airport.

In 2001…severe thunderstorms producing heavy rain and hail… Either washed out or damaged several County roads in the Watkins and Bennett areas.  A small tornado (f0) touched down near Bennett…but did no damage.  Hail as large as 1 3/4 inches in diameter fell near Watkins.  One inch diameter hail was measured near Hudson and Keenesburg.

In 2008…strong winds blew several trees down in Denver… Damaging homes and downing power lines.  A peak wind gust of 67 mph occurred at Centennial airport…with gusts to 60 mph estimated in Denver.  A peak wind gust of 37 mph was measured at Denver International Airport.  An elderly man was killed when a wind damaged tree broke free and crushed him while he attempted to remove it.  The downed power lines caused outages to about 500 Xcel energy customers.

» Click here to read the rest of August 1 to August 7: This week in Denver weather history

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Out of the office

Monday, August 2nd, 2021 6:00am MDT

Out of the Office and in the Mountains

We will be out of the office for a few days while we disconnect and recharge. Be sure to visit the website regularly for the latest forecasts, radar, current conditions and more. See you soon!

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