Thornton, Colorado, USA
UpdatedSun, 07-Mar-2021 1:35pm MST 


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Temperatures remain above normal Thursday, brings a bit of a chance for a storm

Thursday, August 20th, 2020 4:58am MST

Thornton’s weather today looks to be much like yesterday. It will once again be hot and we will see some scattered thunderstorms develop in the afternoon.

Sunny skies start us out then clouds will increase around lunchtime leading to partly clear skies for much of the afternoon. Thunderstorms will again develop in the afternoon with the best chances coming from 3:00pm to 6:00pm. As with yesterday, gusty winds will be the most notable feature although there is just a bit more moisture for them to work with today. High temperatures will once again reach into the mid-90s.

Tonight, any storm activity will end by 9:00pm and skies will gradually clear. Overnight lows will be in the low 60s.

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Wednesday brings slightly cooler temps, better chance for thunderstorms

Wednesday, August 19th, 2020 4:52am MST

Well, it isn’t much, but we will see mercury readings a few degrees cooler than yesterday’s record-setting marks. The afternoon also brings a bit of a chance for thunderstorms although wind looks to be the biggest threat with them.

The day starts out with sunny skies and those will be with us until mid-morning when some cloud cover will then arrive. Highs today will top out in the mid-90s.

Thunderstorms will develop in the afternoon with our best chances coming from about 2:00pm to 5:00pm. There may be some precipitation in them but as mentioned above, wind will be the biggest threat.

Tonight, any storms will come to an end by about 8:00pm and skies will gradually clear. Overnight lows will dip to around 60 degrees.

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Denver hits 100 degrees for the first time of the year, breaks record high for August 18

Tuesday, August 18th, 2020 5:21pm MST

Record High Temperature

For the fourth time this month, the Mile High City set or tied a high temperature record and also recorded its first mercury reading of 100 degrees in almost a year.

As measured at Denver International Airport, Denver’s official high temperature today hit 100 degrees. This easily breaks the record high for August 18 of 98 degrees set in 2013. This was the first time Denver hit 100 degrees this year. The last time was on September 2, 2019. This also marks the 58th time Denver has seen a reading of 90 degrees or higher this year.

Here in Thornton, we matched Denver’s reading of 100 degrees and it was the second time this year we hit the mark. The first came exactly one month ago on July 18.

Looking into the history books, Denver has recorded 100 degree or higher temperatures 93 times since 1872. With the warming climate though, we have been averaging two 100 degree days per year over the past 30 years.

Many are comparing this year to the scorching hot summer of 2012. That year we saw 73 days of 90 degree or warmer temperatures and thirteen of those with 100 degree readings or higher. We also tied Denver’s all-time high of 105 degrees twice that year.

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Tuesday brings on more heat, potentially reaching record-setting territory

Tuesday, August 18th, 2020 5:01am MST

On the plus side, we should see the smoke ease just a bit today. On the negative side, temperatures will be warming even further and could see us tie or set a record high for the date.

Sunny skies start us off and will be with us through the morning. The afternoon will bring a few clouds. As for the smoke, the flow aloft has shifted a bit and that should help keep most of the smoke in the mountains for now.

A few widely scattered thunderstorms may develop in the late afternoon and early evening although we aren’t expecting much out of them, if they form at all. High temperatures today will be pushing close to Denver’s record high temperatures for the date of 98 degrees.

Tonight, skies will be mostly clear with overnight lows in the low to mid-60s.

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Denver sets a new record high temperature for August 17

Monday, August 17th, 2020 6:33pm MST

Record High Temperature

Continuing our seemingly unending string of hotter than normal temperatures, today’s readings hit record-setting territory.

As measured at Denver International Airport, the Mile High City’s temperature topped out at 98 degrees today. That breaks the previous record high for August 17 of 97 degrees set in 2013.

Thornton was just a touch cooler with a high of 96.6 degrees.

This is the third high temperature record set or tied in Denver thus far this month. On August 9th the record high was broken and on August 11th it was tied.

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Monday offers more warm temperatures, just a slight chance for a storm

Monday, August 17th, 2020 4:57am MST

Yeah, we realize these forecasts are sounding a bit like a broken record but it is what it is. The workweek continues the warmer than normal temperatures and will bring periods of smoke.

Mostly sunny skies start us off then any clouds will clear off and sunny skies will be the rule for most of the day. Expect to continue to see haze from wildfire smoke throughout. Highs will top out in the mid-90s. We do see just the slightest chance for a thunderstorm to pop up from about 3:00pm to 8:00pm.

Tonight, skies will clear and overnight lows will drop to the low 60s.

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August 16 to August 22: This week in Denver weather history

Sunday, August 16th, 2020 4:58am MST

This Week in Denver Weather History

August is usually considered one of the calmer weather months in Denver but as our look back in weather history for this week shows, that isn’t always the case.  Thunderstorms and all their associated dangers – lightning, flooding, tornadoes and more – all present a very real danger even this time of year.

From the National Weather Service:


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 women 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.


In 1953…a tornado was sighted 8 miles east of Castle Rock. An unconfirmed tornado was sighted between Denver and Strasburg.  No damage was reported.

In 1963…heavy rain in southeast Denver…Englewood…and Littleton caused flooding of basements and streets.  Over 3.00 inches of rain fell at Cherry Creek Dam.  Lightning caused power failures.  The hardest hit areas were in north- central Denver.  A 12-year-old boy was swept into a conduit by a 3-foot high crest of water.  He was carried 125 feet through the waterway…but was unhurt.  Thunderstorm rainfall totaled only 0.24 inch at Stapleton Airport.

In 1972…a thunderstorm wind gust to 53 mph was recorded at Stapleton International Airport.  Strong winds also occurred in the Littleton area where several trees and utility poles were blown over and a number of windows broken.

In 1978…1 3/4 inch diameter hail was reported in Thornton.

In 1982…heavy rain occurred in the foothills southwest of Denver where 4.50 inches fell in 75 minutes between Evergreen and Conifer.  Nearby…2.66 inches of rain drenched the North Turkey Creek Canyon area in just 15 minutes.

In 1984…scattered slow moving thunderstorms dumped heavy rain across southern metro Denver.  The heavy rain caused some road washouts in Jefferson and Douglas counties.  A bridge was washed out in Douglas County.  Three inches of rain fell in just an hour at Castle Rock…causing heavy silt damage to a home and to nearby drainage ditches.

In 1988…a thunderstorm dumped 2 to 3 inches of rain in southeast Denver and adjacent areas of Arapahoe County in less than 90 minutes.  There was widespread street flooding…and I-25 was closed by 4 feet of water near its intersection with I-225 just south of Denver.  A flood control project in Arapahoe County at greenwood village sustained over 10 thousand dollars damage.  Up to 4 feet of water flooded some basements in the area.  Only 0.44 inch of rain fell at Stapleton International Airport.

In 1990…heavy thunderstorm rains over the Boulder creek and St. Vrain creek drainage basins caused many creeks and drainage ditches to rise in eastern Boulder and southwest Weld counties.  The high waters punched three 30-foot holes in the embankment of a drainage ditch…which traversed through the town of firestone…20 miles north of Denver. A sheet of water 2 to 3 feet deep rushed out onto the streets of firestone…forcing the evacuation of a trailer park and residents from 50 neighboring homes.  No injuries or serious damage occurred except for mud and water damage. Lightning struck and injured 4 construction workers standing in an Aurora field.  They received treatment for minor injuries at a local hospital.  Lightning also struck the roof of a Methodist church in central Denver… Knocking down the highest peak of the steeple.  A half dozen people were in the building…but no one was injured. Slow moving thunderstorms dumped 2 to 3 inches of rain over southeast Aurora in 90 minutes.  The heavy rain accumulated on the roof of a condominium clubhouse…causing the roof to collapse under the weight of the water.  Nearly 300 residents were evacuated from the 200-unit complex because of the structural damage.  The residents were allowed to return to their homes when it was determined the damage was confined to the clubhouse.  No injuries were reported.

In 1993…just west of Fort Lupton…thunderstorm winds blew the tin roof off a cattle shelter into a mobile home… Causing considerable damage to the mobile home.

In 1997…lightning struck a home in Castle Rock sparking a fire.  Damage was estimated at 20 thousand dollars.

In 2000…thunderstorms producing very heavy rain…up to 3.50 inches in spots…caused flooding and flash flooding across metro Denver.  In Commerce City…a 37-year-old firefighter drowned while attempting to rescue a stranded motorist on a flooded street.  The firefighter was wading through the water when he lost his footing and was sucked into a 10 foot deep culvert.  He was swept away before anyone could reach him.  Extensive flooding was also reported throughout Littleton and north Denver.

18 » Click here to read the rest of August 16 to August 22: This week in Denver weather history

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Thornton’s weekend weather remains hot, only slight chances for storms

Friday, August 14th, 2020 4:53am MST

Very little change in the overall weather pattern we have been seeing. Temperatures above normal will continue, albeit with some, slight cooling, and we have only a bit of a chance for a storm or two.

For Friday, sunny skies will be the rule but with some smoke from the wildfires. Highs will top out in the mid-90s. A cool front will push through later today with some breezy winds. Tonight, mostly clear skies will be above with overnight lows near 60 degrees.

Saturday will see temperatures cool slightly with highs in the low to mid-90s. Flow turns northwesterly so we should see less smoke with sunny skies in the AM. The afternoon brings just a slight chance for a thunderstorm. Saturday night into Sunday morning, lows again dip to around 60 degrees under mostly clear skies.

Sunday looks to be much like Saturday. Highs again will be in the low to mid-90s with sunny skies in the AM then some PM clouds and a slight chance for a storm.

Have a great weekend!

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Another hazy, hot day for Thornton’s Thursday

Thursday, August 13th, 2020 4:54am MST

Not much new in our weather forecast today as the same pattern continues. Temperatures will again be well above normal and while we will have few clouds, skies will be hazy from smoke.

Hazy, sunny skies start us off and will be with us through the morning. The afternoon should see some easing of the smoke. Highs today will top out in the mid-90s, well above the average high for the date of 88 degrees.

Tonight, skies will be mostly clear with lows around 60 degree.

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August 9 to August 15: This week in Denver weather history

Wednesday, August 12th, 2020 2:33pm MST

This Week in Denver Weather History

Denver and Colorado as a whole are known for their unusual weather.  This week in particular is notable for one extraordinary event in weather history – clouds of grasshoppers!


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.

» Click here to read the rest of August 9 to August 15: This week in Denver weather history

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