Thornton, Colorado, USA
UpdatedWed, 25-Apr-2018 5:55pm MDT 


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Thornton’s Wednesday to offer a seasonal day with lots of sun, calm conditions

Wednesday, April 25th, 2018 5:00am MDT

Warming up and drying out today. We will enjoy a pleasant spring day with nothing to complain about.

There may be a few clouds at dawn but those will quickly dissipate and we will have clear, sunny skies for the balance of the day. Winds will be light and out of the south. Temperatures start out cold but will steadily warm toward a mid to late afternoon high right near the average high for the date of 64 degrees.

Tonight, clouds will increase a bit with lows near the 40 degree mark.

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A chilly, damp Tuesday in store for Thornton

Tuesday, April 24th, 2018 5:03am MDT

Overnight, rain and snow showers moved in giving us another nice round of moisture. That will ease up during the day but we may see a few sprinkles throughout the daytime hours and temps remain chilly.

We start out under cloudy skies with some light rain / snow falling and lasting until mid-morning. Cloud cover will thin a bit later today but remain pretty dominant. Later this evening, we may again see some light rain. Winds will be breezy out of the north. High temperatures today will top out in the mid-40s, well below the average for today’s date of 64 degrees.

Showers will come to an end this evening and overnight skies will begin to clear. Lows will be dropping to around freezing.

After today, look for warmer and drier weather to last through the weekend.

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

Monday, April 23rd, 2018 5:41am MDT
This week in Denver weather history

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

Certainly April can bring pleasant weather but it also can bring thunderstorms and even heavy, damaging snow as we see in our look back at this week in Denver weather history.

From the National Weather Service:


In 1933…a major storm dumped 16.8 inches of snowfall over downtown Denver when rain changed to snow during the early morning of the 20th and continued through midday of the 22nd. Most of the snow fell on the 21st. Due to melting… The most snow on the ground was 10.5 inches at 6:00 pm on the 21st. Before the snow started…a strong cold front on the evening of the 19th produced north winds sustained to 35 mph with gusts to 37 mph. The strong winds deposited a thin layer of dust on the city. North to northwest winds were sustained to 31 mph with gusts to 35 mph on the 20th and to 29 mph with gusts to 32 mph on the 21st.


In 1957…strong and gusty south to southeast winds raked metro Denver each day. The strongest wind gust of 55 mph occurred on the 21st when blowing dust briefly reduced the visibility to 3/4 mile at Stapleton Airport.


In 1989…unusually warm weather resulted in several daily temperature records being broken in Denver. The high temperature of 89 degrees on the 21st exceeded the record maximum for the month at that time. Daily record high temperatures were either exceeded or equaled with 83 degrees on the 20th…88 degrees on the 22nd…and 85 degrees on the 23rd. The low temperature of 55 degrees on the 22nd equaled the record high minimum for the date.


In 1910…north winds were sustained to 45 mph behind a cold front. Rainfall totaled 0.63 inch.

In 1923…snowfall of 2.0 inches in the city was the only snow of the month and the last measurable snow of the season. Northwest winds were sustained to 25 mph on the 21st.

In 1952…heavy snowfall totaled 7.6 inches at Stapleton Airport. The storm was accompanied by north winds gusting to 33 mph.

In 2001…the second major snow storm in 11 days moved into metro Denver with blizzard conditions developing again across the plains to the northeast of Denver. Snowfall amounts ranged up to 9 inches in metro Denver with up to 23 inches in the foothills. Northwest winds were sustained at 20 to 30 mph with gusts as high as 36 mph at Denver International Airport which was again shut down for nearly an hour by power outages on the 22nd. The outages affected lighting in the concourses…train operations…de-icing and refueling operations…flight information displays…and security screenings. Navigational aids were also affected… Resulting in the cancellation of 58 arriving and departing flights which stranded about 5000 passengers. Across metro Denver storm totals included: 9 inches at Eldorado Springs; 7 inches in Boulder; 6 inches at Ken Caryl…Northglenn and near Sedalia; and 5 inches in Arvada and Morrison. Only 1.7 inches of snow were measured at the site of the former Stapleton International Airport. In the foothills snow totals included: 23 inches near Fritz Peak south of Rollinsville…17 inches near Jamestown…16 inches near Blackhawk…14 inches in Coal Creek Canyon…13 inches at Idaho Springs and near Nederland…11 inches at Aspen Springs…and 10 inches near Bergen Park.


In 1999…a spring snowstorm dumped heavy snowfall over metro Denver and in the foothills. Nearly 3 feet of snow fell in the foothills with over a foot in the city. The heavy wet snow downed power lines in Douglas and Elbert counties. Scattered outages were reported at Parker…Franktown… Sedalia…and Castle Rock. Some residents were without electricity for as long as 20 hours. The inclement weather was blamed…at least in part…for several traffic accidents along the I-25 corridor between Denver and Castle Rock. Snowfall totals included: 32 inches at Idaho Springs; 31 inches on Crow Hill; 29 inches near Evergreen; 26 inches at Chief Hosa and Coal Creek Canyon; 25 inches at Bailey; 24 inches at Floyd Hill; 23 inches at conifer…Genesee…Golden Gate Canyon…North Turkey Creek…and Pine Junction; 13 inches at Broomfield and near Sedalia; 12 inches in Boulder; 11 inches at Louisville and Parker; and 9 inches at the site of the former Stapleton International Airport.

In 2004…heavy snow fell across metro Denver…when low level upslope conditions developed against the foothills and Palmer Divide. Snowfall totals included: 18 inches in the foothills southwest of Boulder…17 inches at Intercanyon and near Conifer…10 inches near Blackhawk and Parker…9 inches at Castle Rock and near Sedalia…7 inches in Centennial… Littleton…and near Lone Tree. Elsewhere across metro Denver…snowfall generally ranged from 2 to 5 inches. Snowfall was 4.7 inches at Denver Stapleton. Northwest winds gusted to 35 mph at Denver International Airport on the 21st.


In 1896…southwest winds were sustained to 39 mph with gusts as high 56 mph. The apparent Chinook winds warmed the temperature to a high of 78 degrees.

In 1904…west winds sustained to 40 mph with gusts to 48 mph warmed the temperature to a high of 69 degrees.

In 1925…southeast winds sustained to 42 mph with gusts to 46 mph warmed the temperature to a high of 76 degrees.

In 1958…west-northwest winds gusted to 48 mph at Stapleton Airport.


In 1885…the worst snow storm since station records began in 1872 dumped a total of 24.0 inches of snowfall on the city. The 23.0 inches of snow recorded on the 22nd and 23rd was the greatest 24-hour snowfall ever recorded during the month of April. Streets were impassable…roofs caved in… Telegraph and telephone wires were downed…railroads were blocked and trains delayed…and most business came to a complete standstill. Estimated losses were reported to 50 thousand dollars. The total snowfall was partly estimated due to melting. Precipitation from the storm totaled 2.79 inches.

In 1915…post-frontal rain during the day and overnight totaled 2.00 inches. Most of the rain fell on the 22nd.

In 1945…6.7 inches of snow fell over downtown Denver. This was the third major snow in a little over 3 weeks…which made this month the 4th snowiest on record. Northeast winds were sustained to 25 mph and light hail fell on the 22nd.

In 2013…a spring storm brought heavy snow to the mountains… with period of moderate to heavy snow to portions of the Front Range Foothills and Urban Corridor. In the mountains and foothills…storm totals included: 18 inches at Niwot Ridge SNOTEL; 16.5 inches near Ward; 13 inches at Arapahoe Basin and Roach SNOTEL…12 inches near Blackhawk; 11.5 inches near Nederland; 11 inches near Allenspark and at Loveland Ski Area; 10 inches near Idaho Springs and Pinecliffe; with 9.5 inches and near Silverthorne. Along the Urban Corridor storm totals included: 7.5 inches near Morrison; 7 inches at the National Weather Service Office in Boulder and Niwot; 6.5 inches near Arapahoe Park and Superior; with 6 inches at Lafayette and Lakewood. At Denver International Airport…4.7 inches of new snowfall was observed.


In 2010…a potent spring storm brought heavy…wet snow to areas in and near the Front Range foothills and widespread rainfall across the adjacent plains. In the Front Range foothills and north-central mountains east of the Continental Divide…storm totals ranged from 15 to 30 inches. Storm totals included: 29.5 inches…3 miles southeast of Pinecliffe; 27 inches…8 miles northeast of four corners; 23 inches at Willow Creek; 22.5 inches… 13 miles northwest of Golden; 21 inches at Never Summer; 17 inches at Eldorado Springs; 16.5 inches…3 miles west of Jamestown. Denver International Airport reported just a trace of snowfall…but measured 2.01 inches of rainfall for the duration of the storm. In addition…a peak wind gust to 54 mph from the northwest was observed at the airport on the 23rd

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

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A mild Monday with a slight chance for a thunderstorm, cold and snow return tonight

Monday, April 23rd, 2018 5:15am MDT

The daytime hours of the first day of the workweek don’t look too bad with above normal temps and just a slight chance for a storm in the afternoon. However, a cold front will push through late this evening bringing better chances for precipitation, including snow, overnight.

The day starts out with mostly sunny skies then will see a gradual increase in cloud cover through the morning and afternoon. Temperatures will warm steadily toward an early afternoon high in the low 70s. After 4:00pm there will be a slight chance for a thunderstorm to move off the high country to lower elevations.

The cold front should arrive after 8:00pm and with it we will see some gusty winds after dark. Overnight some light rain will be possible with a change to snow early tomorrow. Light accumulations, if any, and only on grassy areas will be seen. Lows tonight will be near freezing.

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April 2018 top shots: Monthly photo slideshow

Saturday, April 21st, 2018 4:07pm MDT
A Fox vixen hangs out on a pleasant spring evening. (J Martin)

A Fox vixen hangs out on a pleasant spring evening. (J Martin)

April can be a tricky month weather-wise with everything from mild temperatures to snow to severe weather being possible.  The good thing about that is that it provides plenty of chances for great photos!

April marks a transition between winter and summer for most of the country but for Denver it is especially true as we can see a stunning variety of weather.

The proverbial April showers are certainly a possibility for Denver. Snow? Tornadoes? Thunderstorms? You bet – all can happen!

Throw in our usual wildlife plus the wide variety of birds that return to the Centennial State for the spring and summer and there is a lot going on.

  • Slideshow updated April 21, 2018. 
  • To learn more about how to send your photo to us for inclusion in the slideshow, see below the slideshow.

Showcasing images captured by ThorntonWeather.com readers as well as some of our own, our monthly slideshow covers the entire gamut of weather-related imagery.

Sunsets, sunrises, wildlife and of course every type of weather condition are vividly depicted in images captured from yours and our cameras.

What is missing in the slideshow above?  Your photo!

Our monthly photo slideshow is going to feature images that we have taken but more importantly images that you have captured.  The photos can be of anything even remotely weather-related.

Landscapes, current conditions, wildlife, pets, kids.  Whimsical, newsy, artsy.  Taken at the zoo, some other area attraction, a local park, a national park or your backyard.  You name it, we want to see and share it!

Images can be taken in Thornton, Denver or anywhere across the extraordinary Centennial State.  We’ll even take some from out of state if we can tie it to Colorado somehow.

We’ll keep the criteria very open to interpretation with just about any image eligible to be shown in our slideshows.

What do you win for having your image in our slideshow?  We are just a ‘mom and pop’ outfit and make no money from our site so we really don’t have the means to provide prizes.  However you will have our undying gratitude and the satisfaction that your images are shared on the most popular website in Thornton.

To share you images with us and get them included in the slideshow just email them to us or share them with ThorntonWeather.com on any of the various social media outlets.  Links are provided below.

So come on, get those camera’s rolling!

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Severe Weather 101 – Severe Weather Awareness Week wrap up

Saturday, April 21st, 2018 5:10am MDT
Supercell thunderstorms like this can be beautiful - but they can also be deadly. Do you know what to do when severe weather strikes? (Stormscape Photography / FLICKR)

Supercell thunderstorms like this can be beautiful – but they can also be deadly. Do you know what to do when severe weather strikes? (Stormscape Photography / FLICKR)

Over the past week we have highlighted some of the severe weather hazards that we face in Colorado every spring and summer in our Severe Weather 101 series.  The dangers these present are significant and not to be taken lightly.

Tornadoes grab most of the headlines and certainly are a danger however others like lightning and flooding are more common and actually claim more lives.  We ask all of our readers to please, take the time to review these important articles – they could save yours and your family’s lives!

The National Weather Service has published a nice wrap up of Severe Weather Awareness Week that covers all the basics – see it below.  For more in depth information, please use the links at the bottom to view each article on our Severe Weather 101 series.  Be safe and be weatherwise!

600 AM MDT SAT APR 21 2018


Severe Weather Awareness Week in review…

Severe Weather Awareness Week in Colorado concludes today. During the past week we have presented information and safety rules for tornadoes, lightning and wildfires, floods and flash floods, straight-line thunderstorm winds, hail, and our warning programs.

We will now review some of the most important safety rules in our effort to build a Weather-Ready Nation.

Be weather-wise by staying informed on expected weather in your area. The National Weather Service is typically aware of the potential for severe weather many hours or even days before any severe weather watches or warnings are issued, providing forecast products to heighten your awareness. A Weather Story product is posted each day on National Weather Service Internet pages and Facebook pages which includes a map and text on possible hazardous weather expected within the next seven days.

A Hazardous Weather Outlook is also issued daily with information on possible hazardous weather through the next seven days. A watch is issued when conditions for severe weather or flooding become possible. A warning is then issued when life threatening conditions are imminent or occurring.


Tornadoes can even strike in mountain areas. In 2008 on August 23rd, this rope tornado struck Park County near Eleven Mile Reservoir. Image courtesy Jerry Bivens.

Tornadoes can even strike in mountain areas. In 2008 on August 23rd, this rope tornado struck Park County near Eleven Mile Reservoir. Image courtesy Jerry Bivens.

The best way to protect yourself from tornadoes is to have a plan of action. The safest place to be if a tornado approaches is in a basement or safe room within a well-built structure, or in an underground storm shelter. If none of these options are available, move to a hallway or a small interior room on the lowest floor, usually this is a closet or bathroom. Get under a heavy piece of furniture or in a bath tub and cover yourself with blankets. Remember, the greatest risk of injury from tornadoes is from flying debris.

Modular homes and mobile homes, even those tied down, offer little protection from tornadoes. If a tornado approaches, leave those locations and seek safety in a nearby sturdy building or storm shelter.

If you are driving in open country and see a tornado, if time permits, the best thing to do is simply drive away from the tornado path. Do not take shelter beneath a highway overpass. Wind speeds may actually be higher in these areas and often become collection points for debris.

If you are caught outside and cannot seek shelter inside a sturdy structure, crawl into a culvert or lie down in a narrow ditch or ravine and cover your head. But remember that the worst place to be when a tornado threatens is outside in the midst of flying debris.


Lightning usually kills and injures more people in Colorado than any other thunderstorm hazard. Lightning also causes many wildfires.

The best defense to protect yourself against a lightning strike is to plan ahead and avoid being caught where you might be vulnerable. Check weather forecasts prior to venturing out, especially if you are heading into the mountains. Plan outdoor activities early in the day before storms develop.

If thunderstorms threaten, seek shelter in a building or in an enclosed metal-roof vehicle, making sure all windows and doors are closed. Never seek shelter under an isolated tree. During thunderstorms, stay off corded telephones, away from electrical devices, and away from plumbing. Also get out of shower stalls, bath tubs, swimming pools and lakes when lightning is nearby.

You should wait at least 30 minutes after the last sound of thunder before resuming outdoor activities. When thunder roars…go indoors.

Floods and Flash Floods

The Big Thompson Flood in 1976 claimed the lives of 144 Coloradoans and serves to remind us of the dangers of floods. (USGS)

The Big Thompson Flood in 1976 claimed the lives of 144 Coloradoans and serves to remind us of the dangers of floods. (USGS)

When flooding or flash flooding is possible, you should remain alert and be ready to quickly evacuate to higher ground or climb to safety. Flash floods often occur suddenly and without warning. You need to follow some basic flood safety rules:

  • Do not camp or park your vehicle along streams and washes, particularly during threatening conditions.
  • If you are near a river, be aware of water levels and be prepared to move to higher ground if river levels rise.
  • Do not enter areas that are already flooded.
  • If walking or fishing along a river, be aware that erosion from swift running water can cause river banks to collapse.
  • Never let your children play around high water, storm drains, viaducts or arroyos.

At least half of all flash flood fatalities are vehicle related. While driving your automobile, look out for flooding at highway dips, bridges and low areas. Two feet of moving water will carry away most vehicles. Never attempt to drive across a flooded road. And be especially cautious at night when it is difficult to see flood dangers.

Strong Straight-Line Winds

Straight-line winds from thunderstorms, including microbursts, can become quite strong, even reaching speeds in excess of 100 mph in extreme cases. When thunderstorms approach, high winds can suddenly develop, causing things on the ground to become swift moving airborne missiles with a potential force to injure or kill. As with any thunderstorm, seek shelter before the storm arrives.


This is one of the largest recorded hail stones which is more than 7 inches in diameter and fell in Nebraska in 2003. (NOAA)

This is one of the largest recorded hail stones which is more than 7 inches in diameter and fell in Nebraska in 2003. (NOAA)

Large hail can pose a danger to animals and people. Hail also produces considerable damage to crops and personal property each year in Colorado. Again, get indoors before thunderstorms arrive. A fall of small hail can suddenly change to a fall of very large ice missiles which can injure or kill. Make efforts to protect personal property before storms threaten.

Warning Notification

When thunderstorms threaten, tune to NOAA All-Hazards Weather Radio, The Weather Channel, or your local radio or television stations. Also check the Internet web site from the National Weather Service office serving your area. And if you have a relatively new cell phone you should receive Tornado and Flash Flood Warnings on your phone if you are in the area of the warning.

During threatening weather days, plan the actions you will need to take so that you will be prepared if dangerous weather conditions actually develop.

NOAA’s National Weather Service wishes you a safe severe weather season.

Severe Weather Awareness Week in Colorado concludes today. During the past week we have presented information and safety rules for tornadoes, lightning and wildfires, floods and flash floods, straight-line thunderstorm winds, hail, and our warning programs.


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Thornton’s weekend weather starts unsettled and wet, dries out Sunday

Friday, April 20th, 2018 5:09am MDT

Somewhat of a mixed bag of weather for the three day period. We start out cool and unsettled while receiving some much-needed precipitation then close things out with a nice, dry spring day.

For Friday, a system will be moving in and as it does, we see some good chances for rain. Some lighter, more scattered activity will be possible early with the best chances coming after 3:00pm and lasting through tonight. Mostly cloudy skies will be above with some breezy winds in the afternoon. Highs today will top out in the low to mid-50s.

Tonight, rain showers will continue then, as temperatures drop, we may see a chance to snow in the early morning hours. However, little accumulation is expected and any that does stick should only be on the grassy areas. Overnight lows will be in the mid-30s.

Tomorrow will be a bit of a day of transition. A few, light rain showers will be possible in the morning then in the afternoon activity will come to an end. Some clearing of the skies will also occur in the PM. Highs tomorrow will again be in the low to mid-50s.

Saturday night into Sunday morning skies will continue to clear. Low temps will dip to the mid-30s.

We then close out the weekend with what should be a very nice day Sunday. Expect to see lots of sun, dry conditions and highs in the mid-60s.

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Severe Weather 101 – Lightning and lightning safety

Friday, April 20th, 2018 5:08am MDT
This is NOT the time to be outside. (michaeljames / FLICKR)

This is NOT the time to be outside. (michaeljames / FLICKR)

Of all the weather types associated with thunderstorms – hail, tornadoes, floods, etc – lightning is usually the most dangerous. In the United States there are an estimated 25 million cloud to ground lightning flashes each year and each one is a potential threat to life and property.

During the past 10 years there has been an annual average of 39 lightning fatalities in the United States. Last year, 23 people lost their lives due to lightning.

Colorado is ranked # 2 in lightning related deaths (2001 – 2010) so the danger this presents to life and property is very significant for us. It is interesting to note though that Colorado ranks only 32nd in the number of cloud to ground strikes over that same period. Which means, in short, we have fewer strikes than many other states and yet more deaths.

This highlights the fact that, quite frankly, folks here in Colorado are not aware of the dangers lightning presents and they do not take proper steps to protect themselves. One of the great things about Colorado are the outdoor activities we all enjoy, but there comes a time when we need to head indoors.

» Click here to read the rest of Severe Weather 101 – Lightning and lightning safety

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Severe Weather 101 – Hail and Wind

Thursday, April 19th, 2018 5:06am MDT
Straight line winds can be as damaging as a tornado. This image is from a park in Tennessee. (NWS)

Straight line winds can be as damaging as a tornado. This image is from a park in Tennessee. (NWS)

During the spring and summer months in Colorado, a wide array of severe weather can strike. Tornadoes may grab all the headlines, but straight line winds and hail can do a great amount of damage in their own right – and they are more common.

Straight line winds are winds out of a thunderstorm and are classified as severe when they hit 58 mph. These winds can reach tornado and hurricane force and as a result, cause property damage and can injure and even kill animals and humans.

These winds are usually the result of air cooling rapidly due to precipitation or evaporation. As the cooler air is heavier than the surrounding warmer air, it rushes downward, accelerating toward the ground and spreads out as it hits, much like pancake batter being poured onto a griddle.

» Click here to read the rest of Severe Weather 101 – Hail and Wind

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Mild temperatures, breezy winds and increased fire danger for Thursday

Thursday, April 19th, 2018 5:02am MDT

Unseasonably warm temperatures return to Thornton today. So too, unfortunately, are breezy wind and when coupled with the dry conditions we again see heightened fire danger.

The day starts off pleasant with mostly sunny skies. Cloud cover will increase, particularly in the afternoon, leading to partly clear skies in the PM. Cool temperatures start things out but then we see a steady warm up with highs today in the upper 60s. W

ind speeds will increase in the afternoon and become pretty breezy, continuing into the first half of tonight. The wind coupled with low humidity and dry fuels have prompted a Red Flag Warning to be issued due to increased fire danger. It won’t take much to get a fire started and if one does, it could grow quickly.

Tonight, we will continue to see a good bit of cloud cover with lows around 40 degrees.

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