Thornton, Colorado, USA
UpdatedSun, 13-Jun-2021 2:10pm MDT 


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Lots of sun, cool temperatures for Thornton’s Thursday

Thursday, March 18th, 2021 5:29am MDT

A pretty nice day ahead and one that will help continue to melt away the snow. Lots of sun, cool but comfortable temperatures today.

Clear skies start us off and will be with us most of the day. The afternoon will bring a few clouds but nothing too intrusive. High temperatures are expected to top out in the mid-40s although if we can overcome the chill of the snow cover, it wouldn’t be surprising to see it end up warmer than that.

Tonight, skies will be partly cloudy and lows will drop to the mid-20s. We may see some overnight fog, possibly dense at times.

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Clearing skies Wednesday, temperatures to remain chilly

Wednesday, March 17th, 2021 5:18am MDT

Yesterday’s weak system is moving out having left just a trace of snow. In its wake, cloud cover will begin to ease but temps will remain on the chilly side.

Mostly cloudy skies start us off but by about 8:00 or so we will see a slow, steady decrease in coverage. Overall conditions will be calm with some chilly north winds. High temperatures today will top out in the upper 30s.

Tonight, skies will be mostly clear with overnight lows around 20 degrees.

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Weak system to keep things cold in Thornton, possibly drop a touch of snow

Tuesday, March 16th, 2021 5:17am MDT

While the big storm system has moved away to the central plains, a second, weaker system arrives today. It won’t amount to much, however, just keeping things chilly and maybe delivering a light coat of snow.

The day starts off with some dense fog in the usual areas, primarily along the South Platte and I-76 area. A Dense Fog Advisory is in effect until 10:00am.

Above, skies will be partly clear to mostly cloudy throughout the day. High temperatures will top out in the mid-30s.

We may see a few flakes of snow after noon with the best chances coming between 3:00pm and midnight. Accumulations, if any, will be minimal; a trace to an inch.

Tonight, skies remain mostly cloudy. Any flurries will end before sunrise tomorrow. Overnight lows will drop to the mid-20s.

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Time lapse video: Thornton’s March 2021 blizzard

Monday, March 15th, 2021 8:38am MDT

From rain to blizzard. This is time lapse video from our east-facing webcam showing Saturday AM to this morning. 48 hours in 2 minutes.

Thornton ended up with 20.6 inches. Our anemometer (wind sensor) froze up early yesterday morning so unfortunately no wind was recorded during the height of the event but I sure wasn’t going to climb on the roof to get it unstuck. 😉

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March 14 to March 20: This week in Denver weather history

Monday, March 15th, 2021 6:35am MDT

This Week in Denver Weather History

Think winter is over?  Don’t count on it.  A quick look back at this week in Denver weather history illustrates why.  Many occurrences of winter-like weather can intrude as we see and we don’t even have to look very far back.  It was this week that the March Blizzard of 2003 struck – one of the worst snowstorms in Denver history.


In 1906…an extended cold and blustery period occurred with light snow totaling 14.4 inches over 11 consecutive days. The greatest amount of snow on a single day was 4.0 inches on the 15th.  Only a trace of snow fell on the 12th and 17th. High temperatures were below freezing for the entire period. The coldest were 14 degrees on the 16th and 18 degrees on the 17th.  Both readings were record low maximums for the dates. Low temperatures were mostly in the single digits.  The coldest were 2 degrees below zero on the 16th and 5 degrees below zero on the 19th.  Northeast winds were sustained to 22 mph on the 9th.  North winds were sustained to 36 mph on the 10th…32 mph on the 13th…and 22 mph on the 15th.


In 1880…a protracted cold spell resulted in 8 temperature records being set.  Record low temperatures for the date were set when the temperature dipped to 10 degrees below zero on the 13th and 14th…8 degrees below zero on the 12th and 15th…and 4 degrees below zero on the 16th. Daily record low maximum temperatures were set with 11 degrees on the 12th…12 degrees on the 13th…and 19 degrees on the 15th.


In 1996…a storm system moving across northern Colorado dumped heavy snow in the mountains and foothills and across metro Denver where snowfall ranged from 5 to 10 inches.  A foot of new snow was measured at Nederland with 11 inches at Conifer.  Snowfall totaled 8.0 inches at the site of the former Stapleton International Airport.  Northeast winds gusted to 30 mph at Denver International Airport on the 13th.


In 1906…snowfall totaled 8.0 inches over downtown Denver.


In 1873…a brisk west wind blew a perfect gale during the afternoon and evening.

In 1898…northwest winds were sustained to 52 mph with gusts to 62 mph.

In 1899…west Bora winds were sustained to 50 mph with gusts to 60 mph.

In 1902…west winds were sustained to 40 mph with gusts to 48 mph.

In 1913…strong winds all day behind a cold front made for a blustery cold day as the high temperature climbed to only 25 degrees after a low of 19 degrees.  Northeast winds were sustained to 51 mph with gusts as high as 60 mph.  Only a trace of snow fell.

In 1920…west winds sustained to 43 mph with gusts to 50 mph warmed the temperature to a high of 67 degrees.

In 1923…heavy snowfall of 8.5 inches fell in downtown Denver.  North winds were sustained to 25 mph.

In 1947…heavy snowfall totaled 5.8 inches in downtown Denver.  Northeast winds were sustained to 17 mph.

In 1971…a wind gust to 51 mph was recorded at the National Bureau of Standards in Boulder.

In 1989…a strong pacific cold front produced west wind gusts to 59 mph at Stapleton International Airport.

In 2002…heavy snow developed in the foothills of Boulder County with 9 inches measured near Jamestown and 7 inches near Nederland.  Snowfall totaled only 2.9 inches at the site of the former Stapleton International Airport.  East winds gusted to 29 mph at Denver International Airport.


In 1908…a warm spell resulted in daily record high minimum temperatures on 3 consecutive days:  54 degrees on the 14th…52 degrees on the 15th…and 56 degrees on the 16th… Also the all-time record high minimum for the month of March.  High temperatures ranged from 65 degrees on the 14th to 72 degrees on the 16th.

In 1983…a heavy wet snowstorm buried metro Denver with the foothills receiving the most.  Conifer recorded 34 inches of snow with 4 feet measured at Coal Creek Canyon in the foothills northwest of Denver.  The storm left 6 to 10 inches of snow across metro Denver.  Boulder received 12 to 18 inches.  Flight operations at Stapleton International Airport were limited to one runway for a time.  Some roads and schools were closed…and power outages occurred when wet snow downed lines.  Snowfall on the 15th and 16th totaled 7.2 inches at Stapleton International Airport where north winds gusted to 30 mph.  Maximum snow depth on the ground was only 6 inches due to melting.


In 1902…northwest winds were sustained to 54 mph with gusts as high as 60 mph.

In 1920…southwest winds were sustained to 40 mph with gusts to 48 mph.  The strong but cold downslope winds warmed the high temperature to only 35 degrees.

In 1935…strong winds howled across Boulder.  At Valmont a wind gust to 60 mph was recorded.  No damage was reported.

In 2006…strong winds ranging from 60 to 75 mph were reported in and near the foothills of Boulder County.  In Longmont… Two trees toppled by the strong winds damaged a car.  Winds gusted to 75 mph at the National Center for Atmospheric Research Mesa Laboratory in Boulder.  West winds gusted to 52 mph at Denver International Airport.


In 2000…heavy upslope snowfall occurred in and near the Front Range foothills and over the Palmer Divide to the south of metro Denver.  Snowfall totals from the storm included:  17 inches at Idaho Springs; 16 inches at Aspen Springs; 12 inches in Boulder; 11 inches at Bailey… Chief Hosa…Coal Creek Canyon…Eldorado Springs…Evergreen… And near Morrison; 10 inches at Intercanyon…Ken Caryl Ranch…and near Nederland; 9 inches near Sedalia and in wheat ridge; and 8 inches in Arvada.  Snowfall totaled 5.4 inches at the site of the former Stapleton International Airport.  Northeast winds gusted to 28 mph at Denver International Airport on the 15th.

» Click here to read the rest of March 14 to March 20: This week in Denver weather history

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Following the storm, Thornton warms up, digs out

Monday, March 15th, 2021 6:01am MDT

Well that was one heck of a storm, eh? Thornton ended up with 20.6 inches of very heavy, wet snow. The storm has moved east and today we will see things start to clear and warm up a bit.

A good bit of cloud cover starts off then we should see partly sunny skies for the rest of the day. Temperatures will be slow to warm with highs in the mid to upper 30s.

Tonight, mostly cloudy skies will be above with lows in the mid-teens. Some fog will be possible, especially early tomorrow morning.

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Live blog: Thornton’s March 2021 snowstorm

Sunday, March 14th, 2021 6:37am MDT

ThorntonWeather.com on Facebook, Google+ and TwitterAs Thornton gets hit by a much-needed snowstorm, we are monitoring it very closely and posting regularly to our Facebook page and Twitter feed.  

For comprehensive look at the storm, please monitor our Winter Weather Briefing page.


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Time to spring forward as Daylight Saving Time begins Sunday, March 14

Saturday, March 13th, 2021 6:53am MDT
The United States returns to Daylight Saving Time at 2:00am Sunday, March 14, 2021.

The United States returns to Daylight Saving Time at 2:00am Sunday, March 14, 2021.

The biannual ritual of changing our clocks to adjust for Daylight Saving Time occurs this Saturday night providing yet another signal of the changing of seasons.  The United States will ‘spring forward’ one hour at 2:00am Sunday morning as we begin Daylight Saving Time.

The ritual of changing our clocks twice a year can be met with some resistance as some people struggle to adjust their body’s internal clock.  The start of Daylight Saving Time can be particularly problematic given the one hour less sleep people receive on the night of the change.

However, longer days as we head into the milder months are a very real benefit and for many worth the inconvenience of a lost hour of sleep.  The time change definitely has big effects on how much daylight we enjoy during our normal waking hours.

On Saturday, prior to the change, sunset will occur at 6:05pm but on Sunday the sun won’t disappear over the horizon until 7:06pm.  This affords folks more time in the evening to get started on those spring-time chores and allows us to get outside and enjoy the warming weather.

The March Equinox is also on the horizon.  Spring officially begins at 3:37am on Saturday, March 20.

This year Daylight Savings Time will come to an end on November 7.

Some of the recent history of Daylight Savings Time (from Wikipedia):

Daylight saving time in the United States was first observed in 1918. Most areas of the United States currently observe daylight saving time, with the exceptions being the states of Arizona and Hawaii along with the territories of Puerto Rico, American Samoa, Guam, and the Northern Mariana Islands.

From 1987 to 2006, daylight saving time in the United States began on the first Sunday of April and ended on the last Sunday of October. The time was adjusted at 2:00 AM (0200) local time (as it still is done now).

Since 2007, daylight saving time starts on the second Sunday of March and ends on the first Sunday of November, with all time changes taking place at 2:00 AM (0200) local time.

Daylight Savings Time Schedule

Year DST Begins 2 a.m.
(Second Sunday in March)
DST Ends 2 a.m.
(First Sunday in November)
2021 14 March 2021 7 November 2021
2022 13 March 2022 6 November 2022
2023 12 March 2023 5 November 2023
2024 10 March 2024 3 November 2024
2025 9 March 2025 2 November 2025
2026 8 March 2026 1 November 2026
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Colorado Flood Safety and Wildfire Preparedness Week in Review

Saturday, March 13th, 2021 6:00am MDT
Colorado Flood Safety and Wildfire Preparedness

Colorado Flood Safety and Wildfire Preparedness Week, March 15 – 21, 2015.

Floods and wildfires are arguably the two most common disasters Coloradans face with numerous such events occurring each year.  To better prepare residents for the danger of these disasters, this week is Colorado Flood Safety and Wildfire Preparedness Week.

Each day this week the National Weather Service will be posting public information statements covering a number of different topics about floods and wildfires.  These important messages should be required reading for all Coloradans so they know what to do to prepare for these events and handle them when they occur.

ThorntonWeather.com will be posting each of these messages as a service to our readers.  The first of these messages is below.  Check back each day this week for further topics.

600 AM MDT SAT MARCH 13 2021


Colorado has more than its fair share of floods, flash floods, and wildfires. During the past week, in our effort to build a Weather-Ready Nation, we have presented information to you on how to stay safe and minimize property damage during flood and wildfire threats.

When a flash flood warning is issued for your area, you need to quickly move to higher ground out of drainages or other low spots. It may be just a short run or climb to that higher ground.

Nearly half of all flash flood fatalities occur in vehicles. Do not drive through a flooded roadway. Instead turn around…do not drown. The water may be much deeper than you think, because it may not be possible to see below the surface of flood waters that the roadway has been washed away. One to two feet of water will carry away most vehicles. Additional flood safety information can be found at www.floodsafety.noaa.gov

Areas burned by wildfires are highly susceptible to flash floods, especially within the first two or three years after the wildfire has occurred. Wildfires by themselves destroy much property and occasionally result in fatalities within Colorado. There are actions you can take to protect yourself and minimize the wildfire threat to your property.

If you live near or within a forest or rangeland, you are encouraged to make a defensible space around your home and other structures. Information on how to make a defensible space around your home can be found on the Colorado State Forest Service website at http://csfs.colostate.edu/pages/defensible-space.html

River flooding from snowmelt or persistent rainfall can cause extensive damage to property. There are estimated to be 65 thousand homes and 15 thousand commercial, industrial, and business structures in identified floodplains within Colorado. FEMA has online maps that show if you are in a flood risk area. To access those maps, go to https://msc.fema.gov

If you live in a flood prone area, buying flood insurance is the best thing you can do to protect your home, your business, your family and your financial security. To find an insurance agent and obtain other flood insurance information, go to FEMA’s National Flood Insurance Program web site at www.floodsmart.gov

As a reminder, there is generally a 30-day waiting period from the time a flood insurance policy is purchased to when it goes into effect.

Additional information on floods and wildfires is available from your local National Weather Service web sites…

http://www.weather.gov/denver NWS Denver/Boulder web site
http://www.weather.gov/pueblo NWS Pueblo web site
http://www.weather.gov/goodland NWS Goodland web site
http://www.weather.gov/gjt NWS Grand Junction web site


Colorado Flood Safety and Wildfire Preparedness Week

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Major winter storm set to impact Thornton’s weekend weather

Friday, March 12th, 2021 5:21am MDT

Almost here… The much-anticipated winter storm we have been talking about all week is getting closer to Colorado. Friday will just be chilly and perhaps a bit damp but Mother Nature looks to deliver a wallop Saturday and Sunday. For today, the relative calm before the storm.

Cloudy skies will be above with some drizzle / light rain possible but nothing that will amount to much. Highs will top out around 40 degrees. Tonight, overnight lows drop to below freezing with chances for drizzle increasing. This may lead to some icy roads late tonight and early tomorrow.

Saturday morning the storm arrives and precipitation turns to snow. Moderate snowfall rates will be seen, particularly in the latter half of the day. Saturday night into Sunday morning is when the storm will be at its strongest and deliver its greatest accumulations.

The snow continues throughout the daytime hours Sunday then should begin to gradually ease in the late / afternoon evening.

A Winter Storm Warning will be in effect from 5:00am Saturday to 6:00am Monday. The National Weather Service forecasts 12 to 24 inches with the highest amounts to the west, closer to the foothills.

There remains some uncertainty about the track of the storm and that will be a key factor in snowfall totals. We do believe Thornton stands a decent chance of seeing totals in the 10 to 18-inch range, perhaps higher depending on how things play out.

We certainly would implore you to complete your storm preparations today and just plan on being holed up at home for the weekend.

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