Thornton, Colorado, USA
UpdatedFri, 24-Feb-2017 11:55pm MST 


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Sunny skies, calm conditions and mild temps for Tuesday

Tuesday, September 27th, 2016 5:34am MST

A very simple weather forecast for Thornton today with a total lack of drama. High pressure has settled in with no moisture to be seen and that will lead to a calm, dry and unseasonably warm day.

We will start out with clear skies and that won’t change through the day. No moisture in the air means no clouds. Temperatures today will be climbing to the low 80s, well above the average for the date of 74 degrees.

Live gauges.

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Thornton’s workweek starts with seasonal temps, lots of sun

Monday, September 26th, 2016 5:03am MST

We start out the morning with a bit of a nip in the air as it got quite chilly. That however will wear off quickly and we will enjoy a gorgeous fall day.

Sunny skies will be the rule for Monday lasting throughout the daytime hours. Conditions will be calm, winds light. Temperatures will be warming up to right at or just above the average for the date of 74 degrees.

The balance of the week is going to be nice but also warmer with highs in the general area of the 80-degree mark. The latter part of the week brings slight chances for storms.

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

Sunday, September 25th, 2016 7:14pm MST
This Week In Denver Weather History

September 25 to October 1: 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.


In 1877…smoke from heavy forest fires in the mountains spread over the city on upper wind currents.

In 1935…the first snow of the season was 2.8 inches in downtown Denver. The low temperature dipped to 31 degrees for the first freeze of the season.

» Click here to read the rest of September 25 to October 1: This week in Denver weather history

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Top of Trail Ridge Road closed due to snow

Saturday, September 24th, 2016 6:25pm MST

Ah yes, the changing of the seasons is here and that means our weather conditions go from one extreme to the next.  Following a dry, warm week, Mother Nature brought snow to Colorado’s high country Friday night into Saturday leading to the closure of the highest, continues road in North America.

Rocky Mountain National Park reported dangerous conditions near the top of the Trail Ridge Road resulting in its temporary closure at Rainbow Curve on the east side and Milner Pass on the west side.  Also closed was Old Fall River Road.  Video from Trail Ridge showed a wintry scene looking like the Arctic tundra.

The agency said this was not the seasonal closure – yet.

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Fall Colors 2016: Top spots to view the golden foliage near the Front Range

Saturday, September 24th, 2016 5:00am MST
The leaves in the high country are changing and certainly give meaning to the moniker 'Colorful Colorado.' (ThorntonWeather.com)

The leaves in the high country are changing and certainly give meaning to the moniker ‘Colorful Colorado.’ (ThorntonWeather.com)

This time of year many folks start thinking about heading to the hills west of Denver in search of gold – fall foliage gold.

Where to go?  Below are five of ThorntonWeather.com’s favorite ones near Denver – plus a few further out and some bonus ideas.  After that, we will tell you where you can find a great website that provides regular updates on viewing conditions.


I-70 Corridor – If you’re looking for the easiest route, then this one is for you.  Simply head west on I-70 about 110 miles to Avon.  Between Vail and Avon, both sides of I-70 are lined beautifully with aspen.

Rocky Mountain National Park – One of the most popular summer destinations in the state is of course also a prime spot to view aspen in all their glory.  Once in the park head toward Bear Lake.  Glacier Gorge Junction provides a beautiful spot and you of course also get to enjoy all the splendor that Rocky Mountain National Park has to offer.  Extend your viewing by taking Trail Ridge Road all the way through to the west side of the park and the Grand Lake and Granby area.

Peak to Peak Highway – This little road trip can be a dual purpose trip – gambling and fall foliage viewing!  Take U.S. 6 through Clear Creek Canyon and then 119 through Blackhawk and Central City.  You can of course stop there if your wallet is fat enough and donate some money to the casinos.  From there continue on 119 toward Nederland.  Take highway 72 toward Ward and Allenspark.  There you will find more golden aspen than you can imagine, all with the Continental Divide nearby.

Colorado Fall Foliage - Average Date of Peak Aspen Colors. Click for larger view. (ThorntonWeather.com)

Colorado Fall Foliage – Average Date of Peak Aspen Colors. Click for larger view. (ThorntonWeather.com)

Poudre Valley Canyon –  Heading north on I-25 take Colorado 14 west and into Poudre Canyon and Roosevelt National Forest.  As you continue west you will come very near timberline as you come to Cameron Pass.  Amazing views abound!

Guanella Pass – This is a nice, relatively short drive from Denver.  From C470 take 85 through Bailey and Conifer, a nice drive unto itself.  When you come to the town of Grant, take the Guanella Pass Scenic and Historic Byway north to Georgetown.  The air is pretty thin along the way as you climb in excess of 11,500 views through the Pike and Arapahoe National Forests.  Fair warning – about 10 miles of the road is gravel but it is well maintained.

A couple other possibilities further from the Front Range:

Leadville / Aspen – From Denver take I-70 west to Copper Mountain and then Colorado 91 south over Freemont Pass to Leadville. Along the way there are plenty of viewing opportunities and Leadville is a nice little town to make a stop. From here you can take Highway 24 north back through Minturn and Vail. To extend the drive, take Highway 24 south to Colorado 82 and head toward Aspen. You can stop by the Maroon Bells in White River National Forest to view some of the most photographed mountains in Colorado.

Cottonwood Pass – From Denver take Highway 285 to Buena Vista. Head west on Main Street for seven miles then west on County Road 344 / Colorado 82. From there you start the climb up Cottonwood Pass with absolutely stunning views from the top. If you are up for it, you can continue down the west side of the pass into the Taylor Park area. Be forewarned though that the western half of the pass is unpaved and twisty.

Honorable mentions worth considering:

  • Boreas Pass between Breckenridge and Como (County Road 10)
  • Kenosha Pass on Highway 285 between Bailey and Fairplay
  • Independence Pass (Colorado 82 between Aspen and Twin Lakes)
  • Colorado 103 from Evergreen to Echo Lake. Throw in a drive up Mount Evans for a bonus.

If you do head out, be sure to send us your pictures for inclusion in our monthly photo slideshows!

For more information:

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Thornton’s weekend starts mild, will end much cooler

Friday, September 23rd, 2016 5:11am MST

The three-day period is going to feature some distinctly varying weather conditions. We will start out quite mild with temps well above normal but close things out with very autumn like weather and much cooler temps.

For Friday we will enjoy mostly sunny skies above as we head toward a high temperature in the low to mid-80s. A low pressure system will be moving across the western part of the state and the strong flow from it will bring gusty winds from late morning into tonight. The low humidity, dry fuels and wind will lead to an increased fire danger and a Red Flag Warning is in effect until 8:00pm so please be careful. The afternoon and evening bring us just a slight chance for thunderstorm activity.

The low pressure system continues tracking to our northwest and north but also brings down a cold front Saturday into Sunday. This will bring much cooler temperatures tomorrow with highs down near 70 degrees. We should see a good bit of sun during the day though and just a bit of breezy winds. Tomorrow evening overnight into Sunday morning there will be a slight chance for some light rain, unfortunately not much of a chance and if any does fall, it isn’t expected to amount to much.

Sunday will bring a definite taste of fall. We’ll see a mix of sun and clouds but most notable will be the temperatures. Look for highs to close out the weekend at only around 60 degrees.

Have a great weekend!

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First day of fall brings above normal temps, slight chance for storms

Thursday, September 22nd, 2016 4:04am MST

Hello, autumn! The season arrives with weather conditions similar to what we saw yesterday but with a bit more sun.

We start out the day with partly sunny skies and some areas of patchy fog to watch out for. There will be a bit of an increase in cloud cover later this morning followed by some clearly with mostly to partly sunny skies for the afternoon.

From mid-afternoon into the evening we see just a slight chance for thunderstorms. Temperatures will be topping out in the low to mid-80s with much depending on the amount of cloud cover.

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Temperatures cool a bit for Wednesday, clouds remain

Wednesday, September 21st, 2016 4:59am MST

Not much of a change in Thornton’s weather for today although we will see slightly cooler mercury readings. The clouds will remain and we stand just a slight chance to see some showers.

We start out the day under mostly cloudy skies and while they will ease a bit as the day progresses, we’ll have filtered sun most of the day. This morning a few sprinkles of rain may be seen early on.

Temperatures today will be climbing to the low to mid-80s, an improvement over the upper 80s of recent days. Some thunderstorm and shower activity will be possible this afternoon but most likely will be confined to areas west and south of us.

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Thornton’s Tuesday continues the heat, brings more clouds

Tuesday, September 20th, 2016 4:50am MST

There will be no rest for the heat-weary today as we expect another day with unseasonably warm temperatures. We will have a good bit of cloud cover due to Tropical Storm Paine, now churning off the coast of Baja, as it spins upper level moisture our way.

We start out the day with partly sunny skies and will see gradual increases in the coverage leading to mostly cloudy skies by late afternoon. While Paine brings us clouds, we are not expecting any moisture so it will be another dry one. Temperatures today will be similar to yesterday with highs topping out in the upper 80s.

Keep an eye on the thermometer here.

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Lots of sun, very warm temperatures start Thornton’s workweek

Monday, September 19th, 2016 5:00am MST

With high pressure cemented over the region, we are going to see a very warm day today with dry conditions. Similar conditions will be with us for the first half of the week before a trough digs in and a series of cold fronts cool things off for the weekend.

For today we start out the day with clear skies. With dry conditions aloft, expect to see plenty of sun with few clouds throughout the day. Temperatures today will be pushing toward the 90 degree mark. That is well above the average of 77 degrees for the date but also well below the record of 96 degrees.

Get the extended forecast here.

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