Thornton, Colorado, USA
UpdatedThu, 20-Jan-2022 7:25am MST 


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Above normal temperatures, dry conditions for Tuesday

Tuesday, August 24th, 2021 4:59am MST

Ho hum. Kind of bored with writing essentially the same forecast day after day after day. 😉  Today offers up much of what the last couple of months has in the form of warmer than average temps and dry conditions.

The day starts off with sunny skies and we will see lots of blue above throughout the day. Overall conditions will be dry and calm with some breezy winds in the evening. High temperatures will again top out in the low to mid-90s.

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

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Monday to offer up some toasty temperatures, more on tap the rest of the workweek

Monday, August 23rd, 2021 5:04am MST

If you’re hoping for a break from the heat, don’t look for it in the near future. Thornton can expect above normal temperatures to continue through at least Friday.

For today, sunny skies start us off and will be with us for most of the day. The afternoon will offer a few clouds. Some widely scattered thunderstorms may be seen in the late afternoon / early evening but are not expected to amount to much. High temperatures today will top out in the low 90s.

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

For the balance of the week, highs at or above 90 are expected through Friday. The weekend may offer up some relief but nothing dramatic. More in the extended forecast here.

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August 22 to August 28: This week in Denver weather history

Sunday, August 22nd, 2021 5:05am MST

This Week in Denver Weather History

Lightning is a very real danger here in Colorado.  The outdoor-centric lifestyle we lead oftentimes puts us in situations when we are better off heading for cover.  The dangers of not properly taking shelter when lightning is in the area are highlighted by a number of events in our look back at this week in Denver weather history.


In 1875…grasshoppers appeared in great numbers at 10:00 am on the 19th.  Thousands landed on the ground.  The streets were literally covered with them.  Swarms of grasshoppers were seen on each day.  All gardens in the city were devastated…and in the countryside the grasshoppers were very destructive to ripened grain.  On the 30th the grasshoppers were so numerous as to almost darken the sun.


In 1898…an apparent thunderstorm produced southwest sustained winds to 40 mph with gusts to 43 mph.

In 1903…a late afternoon thunderstorm produced rain…hail… And east winds sustained to 40 mph with gusts to 44 mph.

In 1904…the lowest recorded temperature in August…40 degrees…occurred.  The same temperature also occurred on three consecutive days…August 24…25…and 26 in 1910.

In 1965…heavy rain and hail caused some damage from flooding over northern Douglas County from Castle Rock to Franktown.

In 1981…thunderstorms moved across metro Denver.  At least 5 funnel cloud sightings were reported.  Funnel clouds were seen at 96th Ave. And Sheridan Blvd. and at 92nd Ave. and Federal Blvd. In Westminster and 7 miles north of Stapleton International Airport.  Lightning injured two people in Boulder.  A quarter inch of rain fell in just 5 minutes in Brighton.  Up to 3/4 inch of rain doused Parker in 30 minutes.

In 1983…3/4 inch diameter hail was reported at Kittredge… Along with 0.60 inch of rain in 25 minutes.

In 1984…a thunderstorm dumped 4 inches of rain on Brighton in 90 minutes…causing extensive street flooding in the downtown area.

In 1987…over an inch of rain fell in 24 hours throughout most of metro Denver.  A public library suffered water damage to the ceiling…carpet…and a few books.  Rainfall was 0.76 inch at Stapleton International Airport.

In 1990…lightning knocked out power to about 2500 homes in Lakewood for about an hour.

In 1991…National Weather Service personnel at Stapleton International Airport sighted an apparent tornado briefly on the ground 3 miles west-northwest of the airport.  No damage was reported.

In 1995…lightning struck 3 electrical power substations in Louisville.  Residences of more than 4500 people were without power from 30 minutes to more than an hour.

In 1996…between 1 and 3 inches of rain fell across metro Denver.  As a result…several low lying areas were flooded. A bicyclist was swept into a fast moving creek when he tried to cross a flooded bike path.  The man was washed downstream about 15 feet before getting snagged by a tree stump.  He and a man who tried to rescue him received minor injuries.  The heavy rain caused numerous power outages…false fire alarms…and traffic accidents. In Lakewood…telephone service to around 60 thousand residents was knocked out when a switching center was flooded.  Funnel clouds were sighted near Chatfield Reservoir and Highlands Ranch.

In 2000…lightning sparked a blaze which gutted a 10-unit apartment building in Highlands Ranch.  Twenty-eight people were left homeless.  Damage was estimated at 2 million dollars.

In 2007…severe thunderstorms produced large hail…up to 1 1/4 inches in diameter…in the vicinities of Castle Rock… Elizabeth and Franktown.

In 2013…flash flooding occurred in central Douglas County with numerous road closures reported. One of the closures occurred at the Tomah Road exit along I-25…south of Castle Rock. The closure backed up all I-25 the way to Castle Rock. At Denver International Airport…1.94 inches of precipitation was recorded…which set a new record rainfall for the date. The old record was 0.75 inches… set back in 1953.


In 1987…some locations in metro Denver had a total 3-day rainfall of 2 to 4 inches.  Rainfall totaled 0.96 inch at Stapleton International Airport.


In 1900…northwest winds were sustained to 42 mph with gusts to 49 mph.

In 1921…a thunderstorm cloudburst produced 2.20 inches of rainfall in an hour over downtown Denver.  This is the greatest 1 hour rainfall on record at the official observing site in the city.  Precipitation totaled 2.93 inches…which is the greatest calendar day precipitation ever recorded in August.

In 1941…one man was killed by lightning about 2 miles from the official weather station in downtown Denver.

In 1962…a home near Boulder was destroyed by a lightning- caused fire.

In 1968…strong winds buffeted Boulder briefly during the early morning hours.  At the National Center for Atmospheric Research…winds averaged 55 mph with gusts to 85 mph.  Damage was minor.  Northwest winds gusted to 31 mph at Stapleton International Airport.

In 1977…lightning damaged at least 6 homes in Aurora.

In 2008…a landspout touched down near Westcreek in Douglas County.  One man was seriously injured when he tried to escaped several falling trees in his ATV.  One of the trees struck his back and broke two vertebrae.  Another camper narrowly escaped injury.  Seconds after he back up his truck…a tree came down where it had been parked.

» Click here to read the rest of August 22 to August 28: This week in Denver weather history

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Thornton’s weekend starts off with a couple cooler days, the heat returns later

Friday, August 20th, 2021 5:11am MST

Quite an eventful 18 hours or so we have had, eh? Tornado warnings, rain, hail and then a bonus thunderstorm early this AM. The three day period will be a good bit calmer and, thankfully, we see a break from the heat for a bit.

For Friday, sunny to mostly sunny skies will be above throughout. We will be dry with highs reaching the low to mid-80s. Some breezy winds will be seen from later this morning through the evening. Tonight, lows will dip to the mid-50s under mostly clear skies.

Saturday will see highs similar to today in the low to mid-80s. We will see a few clouds but there will still be plenty of blue above. The afternoon brings just a slight chance for a thunderstorm. Saturday night, any storm activity will end not long after dark. Overnight lows will be in the low 50s. S

unday sees a return of the heat. Highs will again be in the low 90s under sunny skies.

Have a great weekend!

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Thornton to see a cool down Thursday, decent potential for storms

Thursday, August 19th, 2021 5:02am MST

Finally a change in the hot, dry, smoky weather that has dominated this month. Today we will finally see temps cool and, perhaps best of all, have a pretty good chance to see some precipitation.

The day starts off with partly clear conditions and we can expect more of that throughout the day. Temperatures will be topping out in the mid-80s.

A few sprinkles of rain may be seen by mid to late morning but shouldn’t amount to much. This afternoon, the pace should pick up with good chances for showers and thunderstorms. There is some potential for a few of these storms to turn severe with hail and strong winds. At this time, however, we think the worst of it will be to our northeast. It would be wise to keep an eye on things.

Tonight, skies remain partly clear with overnight lows around 60 degrees. A few storms may linger after dark but most activity will be done by midnight.

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Another hot one for Thornton but relief is on the horizon

Wednesday, August 18th, 2021 4:59am MST

Today’s weather doesn’t look much different from yesterday or other recent days. However, we are going to be seeing at least a few days of cooler weather starting tomorrow.

For this morning, sunny skies start us off then we will begin to see some clouds in the afternoon. High temperatures will be topping out in the mid-90s. The late afternoon and evening bring a chance for thunderstorms, just a bit better shot at them than yesterday. Look for some breezy winds to precede them.

Tonight, any storm activity should be done by about midnight and then we will have partly clear skies. Lows will be around 60 degrees.

Looking ahead, a pretty strong cold front will be pushing through and that will lead to cooler temps and better chances for precipitation tomorrow and Friday. See the extended forecast for details.

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Toasty temperatures Tuesday, just the slightest chance for a thunderstorm

Tuesday, August 17th, 2021 5:09am MST

We probably could just copy and paste a forecast from recent weeks for this one as little has changed. Today temps will again be above normal and while there is a slight chance for a storm, wind is the most likely outcome.

The day starts off with sunny but somewhat hazy / smoky skies. The afternoon will see some clouds although they won’t be enough to inhibit temperatures. Highs will be topping out in the mid-90s. Late afternoon will see some isolated thunderstorms but at this time we aren’t expecting much from any that develop.

Tonight, skies will be partly cloudy with overnight lows around the 60 degree mark.

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Monday brings more heat, a return of smoky conditions

Monday, August 16th, 2021 4:49am MST

After a bit of a break from the smoke, it will return again today. The above normal temperatures that we have been seeing will continue, at least for a few more days.

The day starts off with sunny skies. This afternoon we may see a few clouds but nothing too intrusive. The smoke will again return, mostly this afternoon and overnight. Overall conditions will be calm and dry with highs topping out a bit above the 90 degree mark.

Tonight, conditions will be calm with mostly clear skies above. Lows will dip to around 60 degrees.

Looking ahead at the rest of the week, expect more of the hot, dry conditions through Wednesday. After that, we do see the ridge start to break down and allow in some moisture and cooler temperatures. More in the extended forecast here.

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

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

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 MST

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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