Thornton, Colorado, USA
UpdatedMon, 27-Mar-2023 8:00pm MDT 


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Monday starts off the workweek with lots of sun, mild temperatures

Monday, September 26th, 2022 5:00am MDT

If you like your weather forecasts with lots of sun, mild temperatures and boring conditions, this one’s for you. 😉  Thornton will enjoy a pleasant fall day today with mercury readings a good ways above normal.

Sunny skies start us off and will be with us throughout the day. Conditions will be calm and dry. Look for highs today in the low 80s, a good bit above the average high for the date of 75 degrees.

Tonight, skies will be clear to mostly clear with calm conditions. Overnight lows will drop to around 50 degrees.

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September 25 to October 1: This week in Denver weather history

Sunday, September 25th, 2022 5:02am MDT

This Week in Denver Weather History

Colorado’s famously inconsistent weather can be seen in our look back at this week in Denver weather history. Not only do we see damaging thunderstorms and winds but even major snowstorms that deposited more than a foot of the white stuff on the city.

From the National Weather Service:


In 1873…a fire was sighted in the woods near Platte Canyon… Probably caused by high winds blowing sparks among the timber.

In 1896…an apparent cold front produced northeast sustained winds to 40 mph with gusts to 48 mph.

In 1910…a thunderstorm produced sustained north winds to 51 mph. This was the highest recorded wind speed in the city in September at the time.

In 1936…a vigorous cold front produced a deadly dust storm in the city. North winds sustained to 36 mph with gusts to 38 mph produced much blowing dense dust…greatly restricting the visibility. The temperature plunged from a high of 84 degrees to a low of 38 degrees by midnight. The weather observer described the event with the following. “at 6:00 pm the temperature was 82 degrees and the wind velocity was only 4 mph; but with the wind shifting to the north and the barometer rising quite rapidly…the temperature fell sharply. By 6:30 pm…the wind velocity increased rapidly and by 7:00 pm had reached a maximum sustained velocity of 36 mph…bringing with it clouds of dust which had been picked up by gale force winds in southern Wyoming and northern Colorado…covering the city. The visibility was generally reduced to about 1/4 mile; however…the whirling of the dust down the streets and alleys…the visibility was at times somewhat less. Airplanes were grounded…traffic was halted at times…and homes filled with dust. The strong winds damaged electric power and telephone lines…leaving homes in darkness for a few hours in the city and for 18 hours in suburban towns and putting 2500 telephones out of service because of broken lines. An electric lineman was killed while repairing damage by the high winds. The dust storm was followed by rain that began falling at 10:55 pm…which turned to snow during the early morning hours of the 26th. A major snow storm followed on the 27th through the 29th.”

In 1999…high winds developed in the foothills of Boulder County. Winds gusted to 90 mph at Wondervu.


In 1908…apparent post-frontal rain changed to snow overnight and totaled 6.5 inches in downtown Denver. This was the first snow of the season. Precipitation totaled 0.76 inch. North winds were sustained to 39 mph on the 25th.


In 1996…an early season snowstorm brought heavy snow to the Front Range eastern foothills. Snowfall totals included: 8 to 12 inches around conifer…7 inches on Floyd Hill…and 6 inches at both Bailey and Chief Hosa. Snowfall totaled only 4.7 inches at the site of the former Stapleton International Airport. This was the first measurable snow of the season. After the passage of a strong cold front…north winds gusted to 38 mph at Denver International Airport on the 25th.


In 1907…a late afternoon thunderstorm produced hail…0.23 inch of precipitation…and north winds sustained to 24 mph.

In 1927…snowfall of 1.7 inches…mixed at times with sleet… Was the first measurable snowfall of the season.

In 2012…a man was seriously injured when he was struck by lightning outside the Hebrew Educational Alliance as he and his family were getting in their car. The victim stopped breathing but was saved when his wife performed cardiopulmonary resuscitation on him immediately.


In 1936…the heaviest snowfall ever recorded in September and the heaviest snowfall ever recorded so early in the season dumped a total of 16.5 inches of snow on downtown Denver and 21.3 inches at Denver Municipal Airport. The 15.0 inches of snow measured from 6:00 pm on the 27th to 6:00 pm on the 28th is the greatest 24 hour snowfall ever recorded in September. This was the first snow of the season. The snow was intermittent through the 26th…but continuous from early afternoon on the 27th to around midnight on the 28th…except for a period of rain during the afternoon of the 28th which contributed to a loss of depth on the ground. The greatest snow depth on the ground downtown was 13 inches with 8 inches at Denver Municipal Airport. There were no high winds with the storm and traffic was interrupted for only a short period. The storm produced property damage estimated at 7 million dollars. With trees and shrubs in full foliage…the leaves caught and held the heavy water-laden snow…until the branches snapped from the weight. More than 3000 workmen were called to remove the debris and snow from the city. The city firemen who were off duty…as well as all the reserves… were asked to report to their stations. All schools in the city remained open…but attendance was only 50 percent of normal. Grade school students were sent home at noon on the 28th. The early storm caught stockmen with many cattle still in higher ranges. Warm weather followed the snow…which had all melted by the end of the month…except for a few inches in sheltered places. » Click here to read the rest of September 25 to October 1: This week in Denver weather history

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The first weekend of fall to bring seasonal temps, lots of sun, calm conditions

Friday, September 23rd, 2022 4:54am MDT

Well, Mother Nature couldn’t have put together a better period of weather to welcome the changing of seasons. Thornton is going to enjoy lots of sun, temps at or a bit above normal, and calm, dry conditions for the weekend.

For Friday, look for sunny skies above throughout. Highs will top out around 80 degrees. Tonight, skies remain clear with lows dipping to the mid-40s.

Saturday is pretty much a repeat of today. Highs again top out near 80 degrees under sunny skies. Saturday night, lows will drop to the mid-40s and skies remain clear.

Sunday cools down but only slightly. Look for highs in the mid to upper 70s with lots of sun above. The evening weather should be perfect for some Broncos football.

Have a fantastic weekend and enjoy!

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Fall arrives Thursday in Thornton with season-appropriate weather conditions

Thursday, September 22nd, 2022 5:09am MDT

The autumn equinox is here with fall officially arriving at 7:03pm and Mother Nature saw fit to deliver weather conditions appropriate for the new season. Following on yesterday’s cool, damp day, we see somewhat similar conditions today although drier air is beginning to filter in so rainfall will lessen.

Cloudy skies start us off and will be with us most of the day. By mid-afternoon the coverage should start to ease up and we may see some patchy blue. Light rain showers will be possible through the day, perhaps with some thunder in the late afternoon and early evening. High temperatures will top out in the low to mid-60s.

Tonight, any showers will end early and skies will begin to clear. Look for overnight lows around 50 degrees.

Our live radar will keep you up to date on the showers.

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Wednesday brings much cooler temperatures, good chances for rain

Wednesday, September 21st, 2022 6:00am MDT

Our much-anticipated cool down has arrived. With the passage of a cold front Thornton will see a 30+ degree temperature difference today versus yesterday and we will see some welcome precipitation.

Cloudy skies greet us at dawn and will be with us throughout the day. Our warmest temperature readings will actually be seen early with daytime highs around 60 degrees. The mercury will then actually cool a few degrees as the day progresses. A few sprinkles of rain may be seen this morning then chances increase with some light showers expected in the afternoon.

Chances for rain increase in the evening and through the overnight hours when a healthy dose is expected. Showers will then ease after midnight with precipitation becoming lighter. Overnight lows will be in the low to mid-50s.

Keep an eye on current conditions including rain totals with our live gauges here.

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Tuesday to bring one more hot day to Thornton before things cool down

Tuesday, September 20th, 2022 4:57am MDT

Yup, another hot one for us today but a taste of fall lies in waiting and it will quite possibly be the last 90 degree day of the year.

Overall, today’s daytime weather looks much like yesterday’s. We will enjoy sunny skies for the majority of it then see some clouds in the mid to late afternoon. Highs will top out in the low 90s with dry, overall calm conditions.

Tonight, we begin to see a change. A cold front will push through and as it does, winds and cloud cover will increase. Some sprinkles / light rain will be possible after 9:00pm and then through sunrise tomorrow. Overnight lows will dip to the mid-50s.

Looking ahead, Wednesday and Thursday offer up considerably cooler weather with decent chances to receive some precipitation. Have a look at the extended forecast for more.

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Very warm temperatures, dry conditions start off Thornton’s workweek

Monday, September 19th, 2022 4:56am MDT

We have a few more days of summer and Mother Nature is going to remind us of that on two of those with well-above normal temps.

For today, we start out with sunny skies then will see some clouds in the afternoon and evening. High temperatures are going to push to highs near the 90 degree mark. Overall, conditions will be calm and dry.

Tonight, it will be partly cloudy initially then clearing after midnight. Overnight lows will dip to the mid to upper 50s.

We’ll have one more very warm day tomorrow then see a break and a taste of fall for Wednesday and Thursday.

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September 18 to September 24: This week in Denver weather history

Sunday, September 18th, 2022 5:13am MDT

This Week in Denver Weather History

The calendar may still say it is summer for a few more days but our look back at this week in Denver weather history shows that Old Man Winter can still make an appearance.

From the National Weather Service:


In 2018…the high temperature equalled or exceeded 90 degrees for 9 consecutive days; marking the first time such an occurrence has taken place in the month of September. It also brought September of 2018 into a 4-way tie for most 90 degree + days in the month. Previous years included 2017…2005 and 1895. During the streak…4 record high temperatures were either tied or broken…and one record high minumum temperatures was broken.


In 1906…rain on 5 consecutive days totaled 1.61 inches. A thunderstorm occurred on the 17th. High temperatures ranged from 48 degrees on the 16th to 65 degrees on the 15th. Low temperatures were in the lower to mid 40’s.


In 1971…a record breaking early fall snow storm caused extensive damage to trees and utility lines. The heavy wet snow occurred with little wind…but caused record breaking cold temperatures for so early in the season. Snowfall totaled 15.6 inches at Stapleton International Airport with most of the snowfall…12.0 inches…occurring on the 17th. This was the heaviest first snow of the season. The maximum snow depth on the ground was 13 inches. Record low temperatures were set on three consecutive days: 31 degrees on the 17th…23 degrees on the 18th…and 20 degrees on the 19th…which was also a new all-time record minimum for the month at that time. Record low maximum temperatures were set on 4 consecutive days: 48 degrees on the 16th…35 degrees on the 17th…40 degrees on the 18th… And 42 degrees on the 19th.


In 1901…northeast winds were sustained to 42 mph with gusts to 50 mph behind an apparent cold front.

In 1948…the low temperature cooled to only 69 degrees…the all-time record high minimum for the month.

In 1988…a strong cold front blasted metro Denver with high winds. Gusts reached 82 mph in Longmont and 81 mph at Jefferson County Airport near Broomfield where the winds flipped over and destroyed a small airplane. Wind gusts to 60 mph were recorded in Boulder and Wheat Ridge. West wind gusts to 54 mph were clocked at Stapleton International Airport. The strong winds downed trees and power lines and damaged homes and cars. A Longmont man was slightly injured…when a tree fell on top of his car.

In 1990…a slow moving thunderstorm over southwest metro Denver spawned an ominous looking funnel cloud near the intersection of Sheridan Blvd. and U.S. Highway 285. The funnel cloud nearly touched down a few times before lifting back into the main cloud. No damage was reported. Pea to marble size hail and 3/4 inch of rain fell over central and northeast Denver. Numerous streets and underpasses became flooded on Denver’s south side when the heavy runoff backed up storm sewers. Thunderstorm rainfall totaled 1.02 inches at Stapleton International Airport.

In 1993…a severe thunderstorm rolled through southeast metro Denver. Dime size hail was reported in many areas. Straight-line winds from the thunderstorm…measured by a weather spotter at 70 mph…tore the roof off 6 apartments of an apartment complex in Aurora. Heavy rain which accompanied the winds caused major damage to the apartments as well as the contents. Many trees…fences… And power poles were knocked down by the strong winds. Heavy rain flooded roadways in Denver and Aurora. Thunderstorm rainfall totaled 1.08 inches and north winds gusted to 44 mph at Stapleton International Airport where the visibility was briefly reduced to as low as 1/4 mile in heavy rain.

In 1996…a late summer snowstorm struck the northern mountains and Front Range eastern foothills. Golden Gate Canyon received 6 inches of new snow with 5 inches reported at both Nederland and Blackhawk. Thunderstorms produced heavy rain across metro Denver…which was mixed with snow by late evening. Rainfall totaled 0.83 inch at the site of the former Stapleton International Airport and 1.22 inches at Denver International Airport where northwest winds gusted to 39 mph.


In 1955…heavy rains caused flash flooding across portions of metro Denver. Rainfall totaled 1.71 inches at Stapleton Airport.


In 1955…hail stones to 2 1/2 inches in diameter were reported north of Denver. The large stones broke many automobile windshields.

In 1963…hail to 3/4 inch in diameter fell in Westminster.

In 1983…an unusually strong cold front roared through metro Denver during the afternoon hours. At Stapleton International Airport…the temperature dropped 51 degrees… From a sunny 86 degrees to a snowy 35 degrees…in just 7 hours. Strong winds and a wall of blowing dust followed the front. Northeast winds gusting to 36 mph briefly reduced the surface visibility to 1 mile in blowing dust at Stapleton International Airport where only a trace of snow fell later.

In 1996…high winds gusting to 84 mph were measured at Golden Gate Canyon in the foothills west of Denver. West winds gusted to only 25 mph at Denver International Airport.


In 1921…an apparent Bora produced northwest winds sustained to 44 mph with gusts to 64 mph.

In 1955…hail stones 1/2 to 3/4 inch in diameter were reported across parts of the city of Denver.

In 1992…weather observers at Buckley Air National Guard base sighted two tornados southeast of the base. The tornados were short-lived and caused no injuries or damage.


In 1963…heavy rain and hail caused local flooding in southeast Denver. Thunderstorm rainfall was only 0.60 inch at Stapleton Airport on the 20th.

In 1983…the cold front on the 19th brought an unusually cold air mass into metro Denver for so early in the season. The temperature dipped to a daily record minimum of 28 degrees on both days.

In 1995…a vigorous late summer storm brought the season’s first heavy snow to portions of metro Denver. Millions of trees were damaged and power lines downed as 4 to 8 inches of heavy wet snow settled on fully leafed trees in the Boulder and Denver areas. Branches snapped and trees split under the weight of heavy snow…downing power lines. Firefighters responded to numerous transformer fires. Around 100 thousand people were left without electricity in Boulder and Denver areas alone. It took over a week to fully restore power to some areas. Insurance claims were estimated to be around 6 million dollars to homes in metro Denver and about 500 thousand dollars in damage to automobiles. It was estimated that about 80 percent of 125 million dollars worth of city owned trees in Denver were damaged. Snowfall totaled 7.4 inches at the site of the former Stapleton International Airport where the greatest depth of snow on the ground was only 4 inches due to melting. Temperature records were set on the 21st when the thermometer dipped to a record low reading of 27 degrees and climbed to a high of only 36 degrees… Setting a record low maximum for the date. North winds gusted to 29 mph at Denver International Airport on the 20th. » Click here to read the rest of September 18 to September 24: This week in Denver weather history

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Thornton’s weekend to offer up pleasant, late summer weather conditions

Friday, September 16th, 2022 5:19am MDT

This forecast looks pretty good to us. Mother Nature will offer up temps near normal and pleasant conditions for this last weekend of summer.

For today, look for a good dose of sun through the morning. The afternoon will bring some clouds and a slight chance for a shower or thunderstorm. Highs will be in the low to mid-80s. Tonight, skies will clear later and overnight lows will dip to the low 50s.

Saturday brings another nice one. Mostly sunny skies will be above with highs in the low to mid-80s. There is only a slight chance for a PM storm. Saturday night, skies will be clear with lows around 50 degrees.

The weekend closes out on Sunday in fine fashion for the Broncos’ home opener with temps climbing and getting a bit toasty. Look for highs in the upper 80s under sunny skies.

Enjoy the weekend and get outside!

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Thursday will offer a cool down, another chance for thunderstorms

Thursday, September 15th, 2022 5:37am MDT

A chance to perhaps see temps end up a bit below normal in Thornton today. With the cool down, we also have a bit of a chance for afternoon thunderstorms.

Mostly sunny skies start us off, turning to partly sunny this afternoon. Late morning may bring a very light sprinkle of rain. This afternoon, a few thunderstorms may be seen but they are expected to be scattered. Hopefully some make it our way. High temperatures today will top out in the mid to upper 70s.

Tonight, a few lingering storms may be around initially. Then skies will begin to clear. Overnight lows will be in the low 50s.

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