Thornton, Colorado, USA
UpdatedSun, 13-Jun-2021 3:25pm MDT 


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May 9 to May 15: This week in Denver weather history

Wednesday, May 12th, 2021 4:46am MDT

This Week in Denver Weather History

As we get further into spring our look back at Denver weather history begins to show more typical severe weather.  This week in Denver weather history we see plenty of hail, heavy rainfall, a tornado or two and lightning that caused serious injuries.


In 1957…intense heavy rain caused flash flooding on toll gate creek in Aurora where 3 people were killed in a car. Up to 4 inches of rain fell in 5 hours in the Toll Gate Creek basin.  The rain also caused flash flooding on Sand Creek in Aurora and Denver.  Rainfall totaled 3.29 inches at Stapleton Airport with most of the rain…2.34 inches… Occurring on the 9th.


In 1979…4.3 inches of snow fell at Stapleton International Airport where northwest winds gusted to 30 mph on the 8th. Most of the snowfall…2.3 inches…occurred on the 9th. High temperature of only 35 degrees on the 9th equaled the record low maximum for the date.


In 1875…a heavy windstorm swept across the city for most of the day.  West-northwest winds averaged a sustained speed of 31 mph between 6:00 am and 3:00 pm.  The peak wind was sustained to 45 mph at 9:50 am.

In 1918…post-frontal winds were sustained to 40 mph with gusts as high as 43 mph.  Only a trace of rain fell.

In 1941…a tornado was noted at 2:20 pm to the northeast of downtown and was followed by another similar shaped cloud or dust roll estimated 3 miles behind.  Thick dust followed with heavy gusts of wind.  The temperature fell 15 degrees in 10 minutes following the twister.  The mild tornado did little damage except to unprotected frame structures.  Winds were sustained to 50 mph with the passing of the tornado at Stapleton Airport.  It was visible to observers for 10 minutes and was lost from sight as it traveled east into huge rolls of dust.  Hail and rain followed with a few hailstones as large as 1/2 inch in diameter downtown.  No damage was reported from the hail.  Thunderstorm winds sustained to 31 mph produced blowing dust downtown.  Precipitation was only 0.07 inch.

In 1983…streams swollen by recent rain and snowmelt caused an earthen dam to collapse…washing out portions of State Highway 67 near Deckers in southern Douglas County.

In 1992…three boys…ages 11…12…and 16…were struck by lightning while taking cover under a large tree during a thunderstorm in Jefferson County…just 7 miles northwest of Denver.  The three were seriously injured.


In 1889…heavy rainfall totaled 2.15 inches in downtown Denver.  The cold rain was mixed with snow at times overnight.  Temperatures on the 10th ranged from a high of 38 degrees to a low of 32 degrees with north winds sustained to 22 mph.

In 2003…a late spring snowstorm hammered the mountains… Eastern foothills…and urban corridor.  The heaviest snowfall occurred north of interstate 70.  The heavy wet snow caused damage to trees throughout metro Denver and downed power lines.  About 40 thousand people along the urban corridor were without power.  Storm total snowfall amounts included:  11.5 inches in Louisville… 8 inches in Boulder and Broomfield; 7 inches in Thornton…Broomfield…at Denver International Airport… And at the site of the former Stapleton International Airport; and 6 inches 4 miles east of Denver.  Snowfall ranged from 4 to 9 inches across extreme southern weld County.  In the foothills…15 inches of snow fell near Jamestown…9 inches at Rollinsville and Rawah…with 8 inches at Chief Hosa and atop Lookout Mountain. The snow was accompanied by thunder on the afternoon of the 9th at Denver International Airport where west winds gusted to 25 mph on the 9th and north winds gusted to 22 mph on the 10th.

In 2015…from the 9th to the 10th…a strong storm system brought heavy snow to areas in and around Denver. Moderate to heavy rain showers transitioned over to snow by early in the evening on the 9th. Heavy wet snow overnight caused many trees to break under the pressure of the sudden weight. Tree damage ranged from minor to significant…with old growth trees losing large limbs and new trees sustaining fatal damage. Power outages affected about 43350 Xcel Energy customers in metro Denver. The Intermountain Rural Electric Association also reported about 1000 power outages in the Strasburg areas. In the high country…CDOT shut down Interstate 70 between the Eisenhower Tunnel and Silverthorne due to multiple crashes.


In 1875…a windstorm sand-blasted the city from 10:00 am until midnight.  Northwest winds sustained to 60 mph brought clouds of sand…which caused high damage to unfinished buildings.

In 1912…a vigorous cold front produced strong north winds and rain.  North winds were sustained to 48 mph with gusts as high as 60 mph.  Rainfall totaled 1.10 inch.

In 1935…no precipitation occurred…making this one of only two days without precipitation during the entire month.  The other day was the 21st.  Precipitation totaled 4.95 inches for the month.

In 1956…northwest winds gusted to 53 mph at Stapleton Airport where the visibility was briefly reduced to 1/2 mile in blowing dust.

In 1974…strong winds caused 30 thousand dollars in damage to a building under construction in Lakewood.  Microburst winds gusted to 46 mph at Stapleton International Airport.

In 1988…lightning struck a house in Boulder…setting it afire.  The house…valued at 170 thousand dollars…was a total loss.

In 1989…golf ball size hail fell over southeast Denver near the junction of I-25 and I-225.  Hail to 3/4 inch in diameter fell over southeast Aurora.  Only 3/8 inch hail fell at Stapleton International Airport.

In 1991…high winds up to 63 mph raked the eastern foothills. Winds estimated to 50 mph tore a roof from a home in Lafayette.  A tower at Jefferson County stadium in west metro Denver was blown over by the high winds.  No injuries were reported.  Southeast winds gusting to 48 mph at Stapleton International Airport produced some blowing dust.  The temperature climbed to a high of 86 degrees… Equaling the record maximum for the date.

In 2005…severe thunderstorms produced hail as large as 2 inches in diameter in and near Longmont.


In 1918…post-frontal snowfall totaled 4.7 inches in downtown Denver.  Northwest winds gusted to 19 mph on the 10th.

In 1923…winds were strong and gusty on both days.  Northwest winds were sustained to 40 mph with gusts to 44 mph on the 10th.  North winds were sustained to 39 mph with gusts to 46 mph behind an apparent cold front on the 11th.


In 2011…from the 10th to the 12th…a spring snowstorm brought heavy snow to the Front Range Foothills and Palmer Divide. Storm totals included: 18 inches…4 miles south-southeast of Pinecliffe; 16 inches in Coal Creek Canyon; 15 inches…4 miles west-southwest of Eldorado Springs; 13 inches at Gold Hill…12 inches…4 miles west-southwest of Conifer and 4 miles northwest of Elizabeth; 11.5 inches…6 miles southwest of Evergreen and 4 miles east-northeast of Nederland; 11 inches…3 miles east of Jamestown and 10.5 inches…3 miles east of Franktown and 3 miles south of Golden and 10 inches…10 miles north of Elizabeth. At Denver International Airport… 1 inch of snowfall was observed.

» Click here to read the rest of May 9 to May 15: This week in Denver weather history

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Chilly temperatures, rain showers follow Thornton’s stronger-than-expected snow

Tuesday, May 11th, 2021 5:08am MDT

Well, okay, then. Mother Nature threw a bit of a curveball delivering more snow than expected as we received 2.9 inches as of 4:00am. The snow won’t be lasting long but today will remain chilly and wet.

Cloudy skies start us off and will be above throughout the day. There might be a few periods of lighter coverage but don’t expect to see much blue today.

A rain / snow mix will be possible until about 9:00am when showers will turn to all rain. The afternoon may see these increase a bit but we aren’t expecting anything extraordinary.

High temperatures will top out in the low to mid-40s.

Tonight, showers will taper off, ending by midnight. Skies will then clear some but fog can be expected in the early morning hours tomorrow. Overnight lows will again be near the freezing mark.

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Monday to offer cool temps and rain, snow possible overnight

Monday, May 10th, 2021 5:05am MDT

A relatively potent system moves through northern Colorado today. For us, that will mean a chilly, damp day and yes, the dreaded “s-word” (snow) may rear its head tonight.

Cloudy skies will be the rule throughout the day today. Temperatures will remain cool with highs only reaching the mid-40s. A few light sprinkles of rain may be seen this morning. This afternoon, shower coverage will become widespread and we should receive a nice dousing. Some thunder might be mixed in this afternoon.

Tonight, we will remain cloudy with overnight lows dropping to the mid-30s. Rain showers will continue and after midnight, precipitation will have the potential to turn to snow.

We may very well see an inch or so on grassy surfaces by tomorrow morning although best chances for the white stuff will be to our west and south. If you have recently planted or have sensitive vegetation, it might not be a bad idea to get it covered up.

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Thornton’s weekend starts quite warm, will end much cooler and wetter

Friday, May 7th, 2021 5:07am MDT

In a lot of ways, this weekend looks much like the previous one. Things will be starting out pleasant and mild but by the end it will be a good bit cooler and wetter.

For Friday, sunny skies start us off then a few clouds arrive in the afternoon. The afternoon brings some breezy winds and just a bit of a chance for a shower. Tonight, skies will be partly clear with lows in the upper 40s.

Saturday brings the first of a series of a fronts and that will bring chances. Partly sunny skies will be above and then the afternoon will see winds pick up and offer decent chances for thunderstorms and showers. Saturday night, some light showers will be possible with overnight lows around 40 degrees.

Mother’s Day continues the downward trend as another front reinforces the first. Mostly cloudy skies will be above and highs will only be in the mid-50s. Some light rain showers will be possible throughout the day, increasing in coverage and intensity Sunday evening.

Now, just want to throw this out there…  Monday and Tuesday are going to continue the unsettled weather. Most notably, we do see a chance for snow Monday night into Tuesday morning. It won’t amount to much but it is definitely a possibility.

Gotta love springtime in Colorado, eh? Have a great weekend!

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Pleasant spring weather conditions for Thornton’s Thursday

Thursday, May 6th, 2021 4:58am MDT

A break from the unsettled, cool conditions of recent days. Today sees one of those spring days we all love with lots of sun and mild temperatures.

Sunny skies start us off and will be with us throughout the daytime hours. Overall conditions will be calm and dry. High temperatures will be topping out in the low to mid-70s.

Tonight, temperatures will drop to the mid-40s under mostly clear skies. Enjoy!

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Wednesday brings another cool day, another chance for showers

Wednesday, May 5th, 2021 5:04am MDT

Today’s weather looks to be a good bit like we experienced yesterday. We will see some sun, temps will be on the cool side and the afternoon brings a chance for showers.

Partly sunny skies start us off in the morning and we will similar sky conditions for the majority of the day. A few sprinkles of rain may be seen by late morning then early afternoon brings some scattered thunderstorm activity. Any cells that move through should be relatively benign as there isn’t much instability to aid in their development. High temperatures will top out in the low 60s.

Tonight, skies will be clearing and overnight lows will drop to the upper 30s.

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May 2 to May 8: This week in Denver weather history

Tuesday, May 4th, 2021 7:03am MDT

This Week in Denver Weather History

As we enter the month of May, our weather history calendar is as eventful as ever however we start to see a transition with fewer snow events and more typical spring events.  Of note are many events that caused flooding, severe winds, tornadoes, and lightning.


In 1954…a major storm dumped 10.1 inches of snowfall at Stapleton Airport.  Most of the snow…7.5 inches…fell on the 29th and 30th.  The maximum snow depth on the ground was 5 inches on the 30th due to melting.  No strong winds accompanied the storm.


In 1903…post-frontal rain changed to light snow overnight… But totaled only 2.0 inches.  This was the last snow of the season.  Northeast winds were sustained to 45 mph with gusts to 48 mph on the 1st.


In 1898…snowfall totaled 15.5 inches in downtown Denver. Most of the snow…6.2 inches…fell on the 3rd.  Most of the snow melted as it fell.  The greatest snow depth on the ground was only 2.5 inches on the 3rd at 8:00 pm. This was the only snowfall during the month.  Northeast winds were sustained to 22 mph on the 1st.


In 1874…strong winds upset two railroad passenger coaches near Georgetown.  The baggage was retrieved and placed in a heavy…large wagon.  The passengers then seated themselves on top of the baggage.  Another strong gust of wind upset the wagon.  The driver’s shoulder was dislocated…and a passenger’s leg was badly injured. In Denver…northwest winds increased and blew in gusts and heavy winds were observed on the ridge tops.  On the Kansas Pacific R.R. east of Denver…the wind was so strong that it blew the train back several lengths…which caused the train to be about 7 hours late arriving in the city.

In 1901…south winds were sustained to 50 mph with gusts to 60 mph from an apparent thunderstorm with hail.

In 1944…snowfall of 8.3 inches was accompanied by a thunderstorm.  This was the last snowfall of the season and the only snow of the month.  Northwest winds were sustained to 25 mph.

In 1955…southwest winds at speeds of 37 mph with gusts as high as 58 mph caused some blowing dust at Stapleton Airport.

In 1983…1 inch diameter hail fell a few miles south of Bennett.

In 1984…3/4 inch diameter hail fell in Northglenn.

In 1988…I-70 east of Denver was closed for the second straight day…this time due to snow and blowing snow producing up to 2 foot drifts.  While only 2 to 4 inches of snow fell across metro Denver…Strasburg…just east of Denver…received a foot of snow.  North winds peaked to 51 mph at Stapleton International Airport where snowfall totaled only 1.3 inches.

In 1995…lightning struck a house in Westminster sparking an attic fire.

In 2015…a sudden wind gust associated with a dissipating thunderstorm caught some flags attached to a lift and tipped it. Two men were injured when a lift at Civic Center Park in Denver fell on them during Cinco de Mayo festivities. Both men suffered from head injuries…one was in serious condition.


In 1979…heavy rain changed to snow on the 2nd.  Snowfall totaled 3.9 inches at Stapleton International Airport… Where northwest winds gusted to 26 mph.  The greatest depth of snow on the ground was only 1 inch at midday on the 2nd due to melting.  Total precipitation for the 2 days was 1.65 inches.


In 1987…a slow moving storm brought rain…wind…and snow to metro Denver.  Rainfall totaled 1.04 inches at Stapleton International Airport where north winds gusted to 48 mph on the 3rd.  The foothills received 5 to 10 inches of snow.


In 2001…a very slow moving pacific storm system became parked near the Four Corners region…which allowed heavy snow to develop above 6500 feet in the foothills with a mix of rain and snow over lower elevations of metro Denver.  Snowfall totals included:  21 inches atop Crow Hill and at Idaho Springs; 19 inches near Blackhawk; and 18 inches in Coal Creek Canyon…Genesee…and 11 miles southwest of Morrison. Snowfall totaled 6.2 inches at the site of the former Stapleton International Airport.  Precipitation (rain and melted snow) totaled 2.09 inches at Denver International Airport where north winds gusted to 30 mph on the 2nd.


In 1898…heavy snowfall of 6.2 inches fell over downtown Denver.  Most of the snow melted as it fell.  The greatest snow depth on the ground was 2.5 inches during the evening.

In 1907…the all-time lowest recorded temperature in the month of May…19 degrees…occurred.

In 1925…an apparent microburst produced sustained northeast winds to 44 mph with gusts to 52 mph.  Rainfall was only 0.01 inch in downtown Denver.

In 1981…lightning struck 9 golfers at the south suburban golf course.  None were injured seriously.

In 1983…hail 1 1/2 inches in diameter fell at Green Mountain west of Lakewood…with 3/4 inch stones reported in Lakewood.

In 1986…a thunderstorm wind gust to 51 mph was recorded at Stapleton International Airport.


In 1908…rain changed to snow on the evening of the 3rd and continued through the early evening of the 5th. Snowfall totaled 10.0 inches over downtown Denver. This was the last measurable snow of the season. Precipitation totaled 1.51 inches.  North winds were sustained to 23 mph on the 3rd…33 mph on the 4th…and 21 mph on the 5th.  Three temperature records were set. High temperatures of 30 degrees on the 4th and 38 degrees on the 5th were record low maximum temperatures for the dates.  The reading on the 4th was also the all-time record low maximum for the month of May.

In 2007…a slow moving pacific storm system…from the desert southwest…brought a period of unsettled weather to the region.  During the 3-day period…locally heavy snow was reported over parts of the Front Range foothills. Storm totals included:  15 inches near Conifer…14.5 inches west of Jamestown…13.5 inches; 6 miles southwest of Evergreen…and 12.5 inches at Pine Junction.  Severe thunderstorms…producing large hail…up to one inch in diameter were observed in the vicinity of Boulder and Hudson.  Lightning struck a residence in Jefferson County. The roof was hit…causing the attic to catch fire. At Denver International Airport…lightning struck a United Airlines jet as it was pushing away from the gate.  The passengers were taken off the jet and put on another plane.

» Click here to read the rest of May 2 to May 8: This week in Denver weather history

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Some sun returns Tuesday, afternoon and evening bring scattered showers

Tuesday, May 4th, 2021 4:55am MDT

Having deposited a healthy 1.32” of rain, our latest storm system is working its way out. It will be slow to go though and while we will see some sun today, some showers will also be possible.

Partly to mostly sunny skies start us off and then cloud cover will ease further this morning. The afternoon will see the cloud cover begin to increase again. High temperatures today will top out right near the 60 degree mark. Scattered thunderstorms and showers will be possible after noon.

Most activity will wrap up by 6:00pm but a few showers may linger after dark. Tonight, skies will see some clearing with overnight lows around 40 degrees.

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Thornton’s May 2021 preview: From snow to severe storms

Tuesday, May 4th, 2021 4:32am MDT
Thornton, Colorado May 2013 weather preview.

Thornton, Colorado May 2013 weather preview.

Colorado’s famously highly variable weather seems to showcase itself during the month of May when a variety of weather conditions can be seen.

Winter-like temperatures and snow are possible as are mid-summer like temperatures or the more typical spring severe weather.

As the month starts out in 2021 we are going to enjoy unseasonably warm conditions for the first of the month then begin a period of cool, wet weather conditions. Long range forecasts portend an overall warmer than normal month with equal chances of below, at or above normal precipitation.

The month can certainly bring extremes.  Snow is not entirely uncommon during the month, oftentimes causing damage to newly bloomed trees.  More common however is severe weather, particularly in the latter half of the month.  Thunderstorms become more frequent and their associated hazards – lightning, wind, hail and tornadoes – are usual visitors.

For a complete look at what lies ahead for the month of May, check out our full preview here.

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Cool and wet weather conditions start Thornton’s workweek

Monday, May 3rd, 2021 5:02am MDT

The storm system that arrived yesterday is very slowly working its way through and will continue to affect us throughout today. Cool temperatures and light rain will be the general rule.

Cloudy skies start us off and will be with us throughout the day. Winds are going to be breezy and out of the northeast. Light rain will continue to fall this morning then ease up a bit in the afternoon. High temperatures will top out in the mid-40s, about 20 degrees below normal.

This evening, rain will taper off and come to an end by about midnight. Skies will gradually clear overnight and lows will drop to the mid-30s.

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