Thornton, Colorado, USA
UpdatedWed, 25-Nov-2020 1:20pm MST 


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Thornton’s weekend starts off very warm, will end considerably cooler

Friday, September 25th, 2020 4:33am MST

A bit of a mixed bag of temperatures for the three day period. Friday and Saturday are going to see unusually warm readings however, a cold front will cool things down a good bit on Sunday.

For today, sunny to mostly sunny skies will be above with highs again pushing toward the 90 degree mark. Winds will be a bit breezy in the afternoon. Tonight, lows will drop to the mid-50s under partly clear skies.

Saturday sees an increase in cloud cover but at this time it doesn’t appear that will have much of an impact on temps. Look for highs in the upper 80s with some breezy winds. Saturday night into Sunday morning, lows will be near 50 degrees.

A cold front will be pushing through Sunday and that is going to bring a big change in temperatures. Look for highs only in the mid-60s. The day will start sunny and then there will be just a slight chance for a PM shower.

Have a great weekend!

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Thursday to see climbing temperatures, calm, dry conditions

Thursday, September 24th, 2020 4:40am MST

If you thought we were done with the 90 degree days for the season, you may have been mistaken. Thornton looks to string together three, very warm days that may hit or break the mark.

For today, sunny skies are going to be above throughout the day. At this time, it looks like smoke should stay to our north although we may see it intrude a bit this evening. Conditions will be dry and overall calm with the exception of some breezy, late afternoon winds. Highs today are going to push to near the 90 degree mark.

Tonight, skies will be clear with lows in the mid-50s.

After today, Friday and Saturday again are expected to see highs near 90 degrees before we see things cool down on Sunday. More in the extended forecast here.

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Mild temperatures and dry conditions Wednesday, smoke to return this afternoon

Wednesday, September 23rd, 2020 5:00am MST

The first full day of autumn is going to continue our summer-like weather. Temperatures will again be well above normal and smoke from the wildfires will return.

The day starts out with mostly sunny skies and that will continue for most of the day with a few more clouds in the late afternoon. The afternoon is also expected to bring in smoke from the Cameron Peak and Mullen fires. High temperatures today will reach to the mid-80s, about 10 degrees above normal.

Tonight, partly cloudy skies will be above with overnight lows in the low to mid-50s.

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Tuesday brings the arrival of fall, continued mild temperatures and just a slight chance for a storm

Tuesday, September 22nd, 2020 4:58am MST

Today marks the astronomical change of the seasons with fall beginning at 7:30am. While we will see it cool down slightly, temperatures will remain above normal and there is only the slightest chance for a thunderstorm.

Mostly sunny skies start us off then by mid-morning clouds will increase as moisture begins to build aloft. Highs today will top out in the low to mid-80s, slightly cooler than recent days but still well above the average high of 76 degrees for the date.

We see just a slight chance for thunderstorms and showers from about 3:00pm to 9:00pm. At this time, we are not expecting much out of the storms. Some light rain and gusty winds will be about it, if anything.

Tonight, after the storms move out, partly to mostly cloudy skies will be above and overnight lows drop to the mid-50s.

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Monday brings a continuation of the unusually warm, dry conditions

Monday, September 21st, 2020 4:55am MST

If you were looking for a break from the heat, that isn’t going to happen soon. With a high pressure ridge stubbornly in place, we can expect more of the same warm, dry conditions to last through the workweek.

Today starts off with sunny skies but with some haze from wildfire smoke. The afternoon will bring a few clouds and while some showers are possible in the area, they are expected to remain south of us. High temperatures today will again climb to the mid-80s, about 10 degrees above normal for the date.

Tonight, skies will be partly cloudy with lows in the mid-50s.

Looking ahead, expect continued temperatures well above normal to last until Friday. We do have some hope for cooler weather this weekend.

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September 20 to September 26: This week in Denver weather history

Sunday, September 20th, 2020 4:56am MST

This Week in Denver Weather History

Looking back at this week in Denver history we start to see more of the signs that summer is coming to an end and fall and winter are right around the corner.  Summer-like severe weather can still occur but we also start to see more cold temperatures and occasions with snow become more prevalent.

From the National Weather Service:


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.


In 1902…a thunderstorm on the 20th…in advance of an apparent cold front…produced rain…hail…and northwest winds to 40 mph with gusts to 48 mph.  Widespread rain developed behind the cold front and totaled 3.21 inches from the evening of the 20th through the early afternoon of the 22nd.  The 2.70 inches of precipitation recorded from 800 pm on the 20th to 800 pm on the 21st is the greatest 24 hour precipitation ever recorded in the month of September.  The temperature dipped from a high of 80 degrees on the 20th to a high of only 51 degrees on the 21st.


In 1951…4.2 inches of snow fell at Stapleton Airport… Where northeast winds gusted to 27 mph.  This was the first snowfall of the season in Denver…marking the end of the second shortest snow-free period on record…109 days…from June 4th through September 20th.  A trace of snow fell on June 3rd.

In 1984…thunderstorm winds gusted to 56 mph at Stapleton Airport.

In 1992…the only precipitation of the month at Stapleton International Airport…0.01 inch of rain…fell from a brief shower around daybreak.
21-22 in 1870…strong winds occurred in the foothills and in Boulder and Denver.

In 1895…rain changed to snow overnight and totaled 11.4 inches in downtown Denver.  This was the first snowfall of the season and the second heaviest first snowfall of the season on record.  North winds were sustained to 27 mph with gusts to 30 mph on the 21st.

In 2009…an early season storm brought moderate to heavy snow to the foothills of clear creek…Jefferson and Park counties…west and southwest of Denver. A trained spotter…4 miles west-northwest of Conifer… Was the big winner with 14 inches of snow. Storm totals elsewhere generally ranged from 5 to 10 inches.


In 1913…a thunderstorm produced northwest winds sustained to 40 mph with gusts to 44 mph.

In 1946…a trace of snow fell in downtown Denver.  This marked the start of the longest snow season on record… 263 days through June 11…1947…when a trace of snow also fell.

» Click here to read the rest of September 20 to September 26: This week in Denver weather history

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Thornton’s weekend to continue with the warm weather, conditions remain dry

Friday, September 18th, 2020 6:05am MST

Not really any change in our weather for the three day period. Temperatures will continue to be well above normal and while we will have some clouds, no precipitation is expected.

For Friday, we start out sunny then as moisture aloft increases, some clouds will build in the afternoon. Once again, we can expect to have smoke from regional wildfires. Highs will be in the mid to upper 80s. Tonight, partly cloudy skies will be above with lows in the mid-50s.

Saturday will be the warmest day of the weekend with highs pushing close to 90 degrees under mostly sunny skies. Conditions will be calm and dry. Saturday night, partly cloudy skies will be above with lows in the low to mid-50s.

We close out the weekend on Sunday with a pleasant day. Look for highs in the mid-80s under mostly sunny skies.

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Thursday’s weather to bring very warm temps, a bit less smoke

Thursday, September 17th, 2020 5:06am MST

Another day of mild temperatures and dry, calm conditions. We will see warmer temperatures today and, with any luck, less smoke above.

Sunny skies with smoke / haze start us off this morning. This afternoon should see smoke decrease and maybe just a cloud or two appear. High temperatures today will be climbing to the mid-80s.

Tonight, skies remain clear with overnight lows in the low 50s.

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Thornton to see cooler temperatures Wednesday due to a cold front, smoke

Wednesday, September 16th, 2020 4:56am MST

On the plus side, temperatures today will cool down to near normal levels. On the flip side, that will be due to a weak cold front that is also going to pull down smoke into the area.

The day starts off with hazy skies from the smoke. We expect it to become more dense later this morning and through the afternoon. This, coupled with the weak front, will impact temperatures. Look for a high today around the 80 degree mark. Otherwise, conditions will be calm and dry.

Tonight, the smoke will be lingering and overnight lows will drop to the low 50s.

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Mild temperatures and calm conditions Tuesday, smoke moves in

Tuesday, September 15th, 2020 5:04am MST

Thornton will see another day with temperatures well above normal. There would be sunny skies as well but smoke from the West Coast wildfires will be infiltrating in and impacting the blue above.

We expect no clouds at all today as stable, dry air remains in place. However, hazy skies from the smoke will be with us throughout the day and tonight.

Highs today will top in the upper 80s, perhaps hit the 90 degree mark. How warm we get will be impacted by the thickness of the smoke.

Tonight, the haze remains above and overnight lows will dip to the mid-50s.

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