Thornton, Colorado, USA
UpdatedMon, 20-Jan-2020 8:45am MST 


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Thursday sees temps cool to normal levels, overnight may bring some snow

Thursday, January 9th, 2020 5:04am MST

A bit of a change in the weather as a series of disturbances looks to mix things up a bit in the coming days. The change will not be dramatic, however, offering up cooler temperatures and just a bit of a chance for snow.

Today starts with mostly to partly clear skies and then slowly increasing cloud cover as the day progresses. We will cool quite a bit from the unseasonably warm temperatures but only to readings close to the average high for the date of 44 degrees.

Tonight, skies will be mostly cloudy with overnight lows around 20 degrees. Light snow will be possible from about 8:00pm into tomorrow morning. There isn’t much moisture to work with so we are looking at only a trace to maybe an inch if we are lucky.

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January 5 to January 11: This Week in Denver Weather History

Wednesday, January 8th, 2020 5:13am MST

This Week in Denver Weather History

January in Denver is probably best known for the cold and our look back at this week certainly has a number of events that include nasty temperatures. We also many high wind events as well as some significant snowstorms.

From the National Weather Service:


In 1973…the 31st marked the start of a protracted cold spell that extended into January of 1974 when temperatures dipped below zero on 7 consecutive days. Record daily minimum readings occurred on the 3rd and 5th when the temperature plunged to 17 degrees below zero on both days. A record low daily maximum temperature of only 4 degrees occurred on the 5th.


In 1941…a protracted cold spell through January 7…1942… Produced below zero low temperatures on 7 of the 8 days. A low temperature of 2 degrees on the 3rd prevented a string of 8 days below zero. The coldest days during the period were the 1st with a high of 2 degrees and a low of 9 degrees below zero…the 4th with a high of 2 degrees and a low of 11 degrees below zero…and the 5th with a high of 26 degrees and a low of 12 degrees below zero.


In 1940…the first days of the month were characterized by a mixture of drizzle…light snow…and fog. Fog occurred on each day. On the 4th and 5th considerable glazing resulted from freezing drizzle. All objects were coated with a glaze on the windward side. This resulted in very slippery streets…which caused several minor traffic accidents. The glaze was not heavy enough to damage wires and cables.


In 1959…very cold temperatures…to near zero and below…caused power and gas lines…water pipes…and automatic sprinkler systems to break. In Boulder… Merchandise and furnishings were water damaged when pipes burst in a department store…flooding three floors. The temperature was below zero for 38 consecutive hours at Stapleton Airport on the 2nd…3rd…and 4th and plunged to a low of 13 degrees below zero on the 4th.

3-5 In 2017…the first in a series of powerful winter storms brought a period of heavy snow to the north central mountains… Front Range Foothills and Urban Corridor. In the mountains and foothills…the heaviest snowfall occurred along and north of the Interstate 70 corridor. Storm totals ranged from one to around three feet. Eastbound I-70 was closed at Vail and Silverthorne because of poor conditions and several spun-out vehicles. Across the Interstate 25 corridor…heavy snow fell over northern parts of metro Denver north to Loveland. At Denver International Airport…145 flights were canceled. Storm totals in the mountains and foothills included: 19.7 inches 5 miles northeast of Ward…18 inches…17 inches near Brainard Lake and Copeland Lakes; 16 inches…5 miles east-northeast of Nederland and Niwot Ridge SNOTEL; 15.7 inches at Eldora… 14.5 inches at Berthoud Pass; 14 inches at Allenspark and 12 inches at Gross Reservoir. Along the I-25 Corridor…storm totals included: 13.8 inches in Boulder…12 inches at Marston Reservoir…9.5 inches in Niwot…9 inches at Flatiron Reservoir… 8.3 inches in Northglenn; 8 inches at Hygiene…7 inches in Arvada…5 miles west-northwest of Brighton…Frederick… Lafayette…Loveland and 5 miles northeast of Westminster; with 6.5 inches at Ralston Reservoir and Wheat Ridge. At Denver International Airport…there was a mix of rain and snow with only 0.10 inches of snowfall observed on the morning of the 4th.


In 1996…snow began falling across the Front Range foothills and portions of metro Denver on the 4th. Most snowfall amounts ranged from 4 to 6 inches. Icy roads and blowing snow caused a 22 car accident on I-25 north of Denver… Resulting in an 8-mile traffic back-up for several hours. Snowfall totaled 3.2 inches at the site of the former Stapleton International Airport. North-northeast winds gusted to 22 mph at Denver International Airport on the 4th.


In 1871…a heavy gale in Boulder caused 500 dollars damage.

In 1895…northwest winds were sustained to 36 mph with gusts as high as 68 mph in the city.

In 1899…strong winds occurred in Boulder…but caused only minor damage.

In 1911…northwest winds were sustained to 41 mph in downtown Denver.

In 1915…north winds were sustained to 40 mph with gusts to 42 mph behind a cold front…which produced only 1.0 inch of snowfall.

In 1972…warm Chinook wind gusts to 85 mph were recorded in Boulder at the National Bureau of Standards and to 60 mph at Jefferson County Airport near Broomfield. The high winds caused severe blowing snow in and near the foothills… Completely blocking traffic in some areas…closing schools and industrial plants. Houses under construction were damaged…and falling trees damaged cars in Boulder. An apartment building under construction was blown down in the Denver area. Northwest wind gusts reached 58 mph at Stapleton International Airport.

In 1989…during the early morning hours with temperatures in the mid-to-upper 30’s…0.25 inch of rain fell at Stapleton International Airport

In 1994…occasional high winds blew across the eastern foothills. Wind gusts to 84 mph were recorded in southwest Boulder and 74 mph in north Boulder. There were also reports of 70 to 80 mph winds along Colorado highway 93 in Jefferson County from Golden to Boulder. Northwest winds gusted to 37 mph at Stapleton International Airport. No significant damage was reported.

In 1999…strong downslope winds developed in the eastern foothills. A wind gust to 100 mph was recorded at Wondervu… Southwest of Boulder. West-northwest winds gusted to only 37 mph at Denver International Airport.

In 2007…a storm system brought heavy snow to areas along the Front Range. The most snow fell in and near the foothills of Boulder and Jefferson counties. Storm totals included: 17 inches 8 miles northwest of Evergreen…16 inches near Conifer…15 inches southwest of Boulder and at Eldorado Springs…14.5 inches near Genesee…12 inches near aspen and Estes Parks…11.5 inches in Boulder…11 inches at Perry Park… 9.5 inches near Blackhawk…9 inches in Louisville…7.5 inches in Arvada…7 inches near Erie…6.5 inches near Longmont…and 6 inches at Ralston Reservoir and Littleton. Snowfall totaled 5.6 inches at the site of the former Stapleton International Airport.


In 1940…snowfall totaled 5.9 inches in downtown Denver.

In 1975…high winds gusting to over 75 mph caused considerable damage in the Boulder area and minor damage in Jefferson County. In Boulder…one home was unroofed… Several power lines were blown down…and a number of homes and commercial buildings were damaged. Northwest winds gusted to 36 mph on the 5th and 38 mph on the 6th at Stapleton International Airport.

In 1980 high winds in and near the foothills shattered windows…tore roofs from buildings…and caused many power outages. Much of the damage was in Boulder…where winds gusted to at least 82 mph. Wind gusts of 80 to 100 mph were common in the foothills. West winds gusted to only 37 mph at Stapleton International Airport on the 6th.

In 1982…2 to 6 inches of snow fell across metro Denver. Only 1.1 inches of snow were measured at Stapleton International Airport.

In 1983…high winds buffeted the foothills with gusts of 60 to 75 mph recorded in the Boulder area. West winds gusted to only 38 mph at Stapleton International Airport on the 6th.

In 1998…heavy snow blanketed the Front Range foothills. Snowfall totals included: 15 inches 8 miles north of Blackhawk; 13 inches at Evergreen and 5 miles east of Nederland; 12 inches in Coal Creek Canyon; 11 inches 8 miles west of Conifer; 10 inches in Sunshine Canyon northwest of Boulder; 10 inches 11 miles southwest of Morrison; 9 inches in South Turkey Canyon; and 8 inches at Eldora Ski Area. Snowfall totaled only 1.8 inches at the site of the former Stapleton International Airport.


In 1903…northwest winds were sustained to 45 mph with an extreme velocity of 48 mph. The Chinook winds warmed the temperature to a high of 66 degrees…which was a record maximum for the date. The low temperature dipped to only 35 degrees.

In 1962…strong winds caused nearly 14 hundred dollars in damage 2 miles north of Boulder. West-northwest Chinook winds gusted to 33 mph at Stapleton Airport in advance of a cold front that produced northeast wind gusts to 43 mph along with some blowing dust and 0.1 inch of snow.

In 1972…a wind gust to 69 mph was recorded at the National Bureau of Standards in Boulder. Only minor damage occurred. Northwest winds gusted to 33 mph at Stapleton International Airport.

In 2007…a large avalanche swept two vehicles off U.S. Highway 40…near Berthoud Pass…and partially buried them. The slide covered all three lanes of the highway. Eight people were in the vehicles…but only one person was seriously injured. He suffered several broken ribs. The slide was approximately 200 feet wide and 15 feet deep.

6-7 » Click here to read the rest of January 5 to January 11: This Week in Denver Weather History

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Thornton will enjoy a warm Wednesday aided by downslope winds

Wednesday, January 8th, 2020 4:54am MST

With forecast high temperatures almost 15 degrees above normal, we will enjoy a mild day. Driving those temps though will be some breezy downslope winds which might limit your enthusiasm.

We start out with a bit of cloud cover but it will ease as the morning and early afternoon progress. Winds will be light this morning then pick up the pace around noon-time and continue into the evening.

We should avoid any strong gusts but could see some readings up to 25mph or so. The wind will help drive temps up leading to highs in the upper 50s.

Tonight, mostly clear skies will be above with lows in the mid-20s.

Keep an eye on the temps and winds here.

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Tuesday starts with wind but the blowing will ease, temps will be well above normal

Tuesday, January 7th, 2020 4:56am MST

The wind of the last 36 hours or so is blowing its last breath this morning. As it starts to die down, we will see a day with a good bit of sun and very mild temperatures.

Clear skies start us off and by late morning a few clouds will arrive giving mostly sunny skies in the afternoon. Breezy winds are going to continue early but by mid to late morning they will ease. High temperatures today will be in the mid to upper 50s, well above the average high for the date of 44 degrees.

Tonight, partly cloudy skies will be above with lows in the mid-20s.

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Thornton’s workweek starts with seasonal temps but wind will be along for the ride

Monday, January 6th, 2020 5:07am MST

Normally, sunny skies and temps near normal would be something to be happy about. Today, however, with gusty winds expected throughout the day, your enthusiasm about the weather will be lessened.

Clear skies start us off and will be with us throughout the day. Temperatures start on the cold side but will warm to a high right near the average for today’s date of 45 degrees.

The main story today will be the wind which is already blowing pretty good and will continue through the day. Gusts pushing toward 40mph will be possible.

Tonight, the wind will ease some after about 8:00pm but remain a bit breezy. Skies will be mostly clear with lows in the mid-20s.

Keep an eye on current wind speeds with our live weather gauges here.

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December 2019 weather recap: Warmer than normal temps, little snowfall

Sunday, January 5th, 2020 7:42am MST

We closed out 2019 with a change from the cool, wet conditions of the previous two months. December saw the opposite conditions as average temperatures were above normal and snow a rarity.

Storm systems did move through Colorado and the Rocky Mountain region and while the high country saw plenty of snow, these storms evaded the Front Range for most of the month. Temperatures were never particularly warm but overall, the average temp was warmer than normal in Thornton.

On the 5th of the month, we saw a respectable bit of rain instead of snow. Finally, a light snowfall on the 14th was the first snow of the month. We then stayed dry until the 28th when we received our first – and only – appreciable snowfall of the month.

Thornton’s overall average temperature for the month came in at 31.9 degrees. This was a good bit warmer than Denver’s long term average for December of 30.0 degrees. Out at Denver International Airport where the Mile High City’s official records are kept, it was warmer with an average of 33.7 degrees.

Temperatures in Thornton ranged from a high of 64.6 degrees on the 22nd down to a low of 7.2 degrees on the morning of the 30th. Denver recorded a maximum of 67 degrees and its minimum of 3 degrees on the same dates.

In terms of precipitation, Denver averages 0.35 inches during December. Thornton fell short of that with 0.28 inches while Denver had just a touch more with 0.30 inches.

A mere 2.8 inches of snow was recorded in Thornton during the month and Denver had an identical number. These were well short of the 8.7 inches December typically brings.

Click here to view Thornton’s December 2019 climate report.

Thornton, Colorado's December 2019 Temperature Summary. (ThorntonWeather.com)

Thornton, Colorado’s December 2019 Temperature Summary. (ThorntonWeather.com)

Thornton, Colorado's December 2019 Precipitation Summary. (ThorntonWeather.com)

Thornton, Colorado’s December 2019 Precipitation Summary. (ThorntonWeather.com)

851 AM MST WED JAN 1 2020




                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
 HIGH              79   12/05/1939
 LOW              -25   12/22/1990
HIGHEST            67   12/22        62       5       63  12/21
LOWEST              3   12/30        -4       7        0  12/31
AVG. MAXIMUM     45.3              42.8     2.5     46.1
AVG. MINIMUM     22.1              17.1     5.0     18.8
MEAN             33.7              30.0     3.7     32.5
DAYS MAX >= 90      0               0.0     0.0        0
DAYS MAX <= 32      6               5.8     0.2        4
DAYS MIN <= 32     27              29.4    -2.4       31
DAYS MIN <= 0 0 2.0 -2.0 1 PRECIPITATION (INCHES) RECORD MAXIMUM 5.21 1913 MINIMUM 0.00 1881 TOTALS 0.30 0.35 -0.05 0.03 DAILY AVG. 0.01 0.01 0.00 0.00 DAYS >= .01         2               4.1    -2.1        1
DAYS >= .10         2               1.1     0.9        0
DAYS >= .50         0               0.1    -0.1        0
DAYS >= 1.00        0               0.0     0.0        0
 24 HR. TOTAL    0.18   12/28 TO 12/28           12/31 TO 12/31

 TOTAL            2.8               8.7
RECORD DECEMBER  57.4    1913

HEATING TOTAL     964              1086    -122      999
 SINCE 7/1       2499              2468      31     2372
COOLING TOTAL       0                 0       0        0
 SINCE 1/1        916               769     147     1026

 EARLIEST     09/08/1962
 LATEST       06/08/2007
EARLIEST                        10/07
LATEST                          05/05

AVERAGE WIND SPEED              9.1

AVERAGE SKY COVER           0.50
NUMBER OF DAYS FAIR            7
NUMBER OF DAYS PC             19


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Thornton’s January 2020 preview: Cold temps, not much snow the norm

Saturday, January 4th, 2020 5:26am MST

Denver's January weather and climatology preview for 2013.As we begin the new year the winter chill begins to set in.  While January can see its share of extremes, the month historically sees stable temperatures and is usually relatively dry.

January ranks as the second coldest month in Denver next to December with average temperatures remaining virtually the same from the start to the end of the month.

In terms of snowfall, the month only ranks as the fourth snowiest and it is not uncommon for it to be quite dry.

What does January 2020 hold for us?  Follow the link to find out.

For the complete January preview including a look at historical averages and extremes, click here. 

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Thornton’s weekend to feature lots of sun, warmer than normal temps

Friday, January 3rd, 2020 5:11am MST

A pretty good looking three-day period in store for us. Slightly above normal temps will be in place for two of the three days and Saturday will be quite mild.

For today, sunny skies will be above throughout. Highs will be in the mid to upper 40s and the afternoon will bring some breezy winds. Tonight, skies remain mostly clear and lows will be in the mid-20s.

Saturday will be the warmest day of the period aided by downslope flow. Looks for highs in the mid to upper 50s under sunny to mostly sunny skies. Overnight Saturday into Sunday morning, winds will be breezy with mostly clear skies and lows in the mid-20s.

Sunday wraps things up nicely with a good bit of blue above and highs in the mid-40s.

Have a great weekend.

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Thursday to offer near normal temps, a good bit of sun and some breezy winds

Thursday, January 2nd, 2020 5:07am MST

A day ahead for us that could best be described as “seasonal.” Temps will be right near average for the date with mostly clear skies.

We start out with some cloud cover but that will ease and we will enjoy mostly sunny skies for the majority of the day. Winds will be light initially then become a bit breezy in the afternoon but not near as bad as we saw yesterday. Temperatures will top out right near the average high for today’s date of 43 degrees.

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

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Thornton welcomes in 2020 with mild temps but also breezy winds and some clouds

Wednesday, January 1st, 2020 5:21am MST

Hello, 2020! We begin the new year with a mild day and temps well above normal. A good bit of cloud cover and some breezy winds will also be featured today.

The day starts with mostly clear skies but clouds will be increasing leading to mostly sunny conditions for most of the day. Winds will be light initially then be picking up and becoming breezy and out of the west. The downslope flow will help drive temperatures to the mid-50s.

Tonight, partly clear skies will be above and overnight lows will drop to the mid-20s.

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