Thornton, Colorado, USA
UpdatedThu, 23-Nov-2017 3:15pm MST 


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Hot News from the Antarctic Underground

Tuesday, November 7th, 2017 12:10pm MST

Illustration of flowing water under the Antarctic ice sheet. Blue dots indicate lakes, lines show rivers. Marie Byrd Land is part of the bulging “elbow” leading to the Antarctic Peninsula, left center. » Click here to read the rest of Hot News from the Antarctic Underground

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Cold and light snow main features for Thornton’s weather Tuesday

Tuesday, November 7th, 2017 5:10am MST

As expected, we are waking up to a bit of the white stuff this morning. The wintry weather won’t last long as a return to seasonal, dry conditions comes tomorrow and should last through the weekend.

Cloudy skies will be the rule throughout the daytime hours today. Temperatures start out below freezing and minimal warming will be seen with highs topping out in the mid-30s.

Light snow will continue to fall in the pre-dawn hours then ease very slowly through the day. Some additional, light accumulations will be possible, mainly on grassy areas.

Tonight, skies will begin to clear allowing overnight low temperatures to dip well into the 20s.

Looking ahead, high pressure is expected to build allowing us to quickly shake off this storm. Plenty of sun, dry conditions and temperatures in the 50s and 60s should be the rule for the rest of the week. See more in our extended forecast here.

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Thornton’s Monday to offer cool temps, snow arrives tonight

Monday, November 6th, 2017 5:51am MST

A bit of a mixed bag of weather today. Daytime conditions will be similar to yesterday with temperatures approaching near normal. This evening and tonight though the situation changes a good bit with snow arriving.

The day starts off with mostly cloudy skies then we should see some breaks in the coverage later in the morning. Partly sunny skies will be the general rule. Temperatures will climb toward a high in the low to mid-50s, not too far off the average for the date of 57 degrees.

The storm system will begin to make itself felt right about rush hour but only in the form of some light rain / sprinkles. Tonight, as temperatures cool, we expect to begin to see snow with the majority expected to fall between 11:00pm tonight and 5:00am tomorrow.

We could see an inch or two out of the system, nothing extraordinary but enough to make a mess. Light snow will continue through much of the day today.

For the latest, check out our Winter Weather Briefing Page here.

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November 5 to November 11: This week in Denver weather history

Sunday, November 5th, 2017 4:18am MST
This Week In Denver Weather History

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

Our look back at this week in Denver weather history is dominated with two types of events: snow and wind. November is our second snowiest month and we see many significant snowfall events in the past. Wind is a fact of life on the plains and in Denver and damaging events have occurred with relatively frequency as we can see below.

From the National Weather Service:


In 1946…a major snow storm dumped 30.4 inches of heavy snowfall downtown and 31.0 inches at Stapleton Airport. The winter storm closed schools and disrupted all forms of transportation in the city. The greatest depth of snow on the ground was 28 inches at the airport. The duration of the snowfall…from 4:22 am on the 2nd to 3:08 am on the 5th… A total of 70 hours and 46 minutes…is the second longest period of continuous precipitation on record and the second heaviest snowfall of record at the time in Denver. The 17.7 inches of snowfall on the 2nd and 3rd was the greatest 24- hour snowfall ever recorded during the month of November. Buses and street cars had a difficult time…and many cars were abandoned along roadsides and streets for several days. Secondary roads in rural areas were blocked for 2 to 3 weeks. Several buildings in the city collapsed or were damaged from the weight of the heavy snow. Football games were canceled. Livestock losses were high over eastern Colorado. The precipitation from this storm alone exceeded the greatest amount ever recorded in Denver during the entire month of November previously. The precipitation recorded downtown was 2.03 inches…and the previous record for the entire month of November was 1.95 inches in 1922. North winds were sustained to 26 mph on the 2nd.


In 1933…the first measurable snow of the season totaled only 2.5 inches. This was the only measurable snow of the month. Northwest winds were sustained to 27 mph on the 4th.

In 1951…heavy snowfall of 5.7 inches was measured at Stapleton Airport where northwest winds gusted to 32 mph.


In 1896…west Chinook winds sustained to 44 mph with gusts to 46 mph warmed the temperature to a high of 56 degrees in the city.

In 1919…a rare November thunderstorm produced a mixture of rain and snow during the evening. Precipitation totaled only 0.14 inch with only a trace of snow. Northeast winds were sustained to 39 mph with gusts to 44 mph.

In 1948…a west-northwest wind gust to 50 mph was recorded at Stapleton Airport.

In 1994…winds gusted to 76 mph on the summit of Squaw Mountain…5 miles south of Idaho Springs.

In 2000…snow fell in the foothills west of Denver and across the southern suburbs. Snow totals included 6 inches near Evergreen…11 miles southwest of Morrison… And 7 miles south of Tiny Town and 5 inches in Aurora and Parker. Snowfall totaled 5.5 inches at the site of the former Stapleton International Airport. Northeast winds gusted to 26 mph at Denver International Airport where the visibility was reduced to 1/4 mile in heavy snow at times.


In 1938…heavy snowfall totaled 7.5 inches over downtown Denver. North winds were sustained to 16 mph with gusts to 19 mph on the 5th.


In 1918…rain was mixed with and changed to snow…which became heavy and totaled 8.1 inches in downtown Denver. North winds were sustained to 21 mph with gusts to 23 mph.


In 1962…west winds gusted to 55 mph…briefly reducing the visibility to 1 1/2 miles in blowing dust at Stapleton Airport. The strong winds blew all day.

In 1989…high winds to 62 mph were recorded in Boulder. Northwest winds gusted to 33 mph at Stapleton International Airport.

In 1991…strong westerly Chinook winds blew into metro Denver with gusts to 88 mph recorded at Rollinsville and to 51 mph in Boulder. Later…northeast winds with gusts of 30 to 40 mph were common across all of metro Denver behind a cold front…which produced only 0.2 inch of snowfall at Stapleton International Airport.


In 1958…a strong cold front produced northeast wind gusts to 52 mph at Stapleton Airport where some blowing dust was observed.

In 1980…Chinook winds at sustained speeds of 40 mph were recorded with a peak gust to 71 mph measured at Wondervu southwest of Boulder. West winds gusted to 25 mph at Stapleton International Airport.

In 1989…strong winds buffeted many foothills areas. Wind gusts of 60 to 70 mph were recorded in Boulder and Longmont. Northwest winds gusted to 43 mph at Stapleton International Airport.

In 1996…wind gusts to 75 mph were recorded at Golden Gate Canyon and at the Rocky Flats Environmental Test Facility northwest of Denver. Northwest winds gusted to 40 mph at Denver International Airport.

In 1998…upslope conditions…coupled with a moist and unstable air mass…allowed heavy snow to develop in the foothills west of Denver. Snowfall generally ranged from 4 to 6 inches…but 7 inches were measured 4 miles south of Evergreen. Only 1.2 inches of snow fell at the site of the former Stapleton International Airport. This was the first measurable snow of the season.


In 1969…wind gusts to 48 mph in downtown Boulder caused minor damage.


In 1896…southwest Chinook winds sustained to 42 mph with gusts as high as 46 mph warmed the temperature to a high of 53 degrees.

In 1977 near-blizzard conditions in blowing snow caused the closure of I-70 to the west of Denver in clear creek canyon and east of Denver to Limon. Northeast wind gusts to 46 mph were recorded at Stapleton International Airport where snowfall totaled only 1.1 inches.

In 1984…a rare November thunderstorm produced west winds gusting to 31 mph…but only 0.04 inch of rain at Stapleton International Airport.

In 1996…high winds gusting from 80 to 100 mph were recorded at Wondervu in the foothills southwest of Boulder. West northwest winds gusted to 32 mph at Denver International Airport.

In 2006…the temperature in Denver climbed to a high of 80 degrees. This was the first time the temperature had ever exceeded the 70’s in November since records began in 1872. This new all-time record maximum temperature for the month of November was also a new daily record and the highest temperature ever recorded so late in the season.


In 1897…west winds were sustained to 45 mph with gusts as high as 50 mph in the city.

In 1919…post-frontal heavy snowfall totaled 8.4 inches over downtown Denver. Most of the snow…6.6 inches…fell on the 9th. North winds were sustained to 26 mph with gusts to 30 mph on the 8th.

In 1950…a major winter storm dumped 10.4 inches of snow at Stapleton Airport with the most snow…7.8 inches…falling on the 8th. East winds gusted to 31 mph at Stapleton Airport on the 8th. Snowfall totaled 8.2 inches in downtown Denver.

In 1958…strong winds caused some damage in Boulder. West- northwest winds gusted to 40 mph at Stapleton Airport on the 8th.

In 1975…heavy snowfall hit metro Denver. Snowfall at Stapleton International Airport totaled 8.0 inches and east winds gusted to 21 mph. Power outages caused by the storm affected over 10 thousand people in metro Denver.

In the foothills west of Denver…10 to 15 inches of snow fell. The storm produced the greatest 24-hour precipitation…1.29 inches…ever recorded during the month of November in the city.

In 1983…metro Denver received 4 to 8 inches of snow with the heaviest amounts near the foothills. It was the first measurable snow of the season in Denver. Only 1.8 inches of snow fell at Stapleton International Airport where north winds gusted to 20 mph.

In 1989…strong winds hit the Front Range. On the 9th…the wooden frame of a house under construction in Boulder was blown down. The previous evening a power outage blackened Nederland. Wind gusts to 95 mph were recorded 4 miles south of Rollinsville with 97 mph on Fritz Peak near that town. At Stapleton International Airport…northwest winds gusted to 45 mph on the 8th and to 38 mph on the 9th.

In 1998…another upslope snow event developed in the Front Range foothills. The heaviest snowfall occurred in west central Jefferson County where 14 inches were measured 8 miles west of Conifer. Other snowfall totals included: 10 inches at Evergreen and 9 miles northwest of Bergen Park; 9 inches at Genesee…Nederland…and near the Chief Hosa exit on I-70; and 8 inches in Coal Creek Canyon. On the 9th…snowfall was 2.6 inches at the site of the former Stapleton International Airport. North-northeast winds gusted to 30 mph at Denver International Airport on the 9th.


In 1985…Indian summer came to an abrupt end when a winter storm dumped 10 to 18 inches of snow in the Front Range foothills and 6 to 10 inches across metro Denver…snarling traffic and causing flight delays of up to 3 hours at Stapleton International Airport. The temperature plunged from a high of 66 degrees on the 8th to a low of only 13 degrees on the 9th…after the passage of a vigorous cold front with northeast winds gusting to 32 mph. The temperature climbed to only 19 degrees on the 10th…setting a record low maximum for the date. Snowfall totaled 7.3 inches at Stapleton International Airport with most of the snow…7.1 inches…falling on the 9th.


In 1939…a trace of snow fell over downtown Denver. This snow…along with a trace of snow on the 2nd…was the only snow of the month…ranking it…along with other months…the second least snowiest November on record. Precipitation of 0.01 inch was the only precipitation of the month…making this the second driest November on record.

In 1944…the first killing frost of the season occurred in the city when the low temperature dipped to 35 degrees. This is the latest date for a killing frost ever recorded in Denver.

In 1946…heavy snowfall totaled 7.7 inches over downtown Denver. This was the second heavy snowfall in less than a week. Northwest winds were sustained to 26 mph.

In 1995…strong downslope winds gusted between 50 and 57 mph at Erie and Boulder. West wind gusts to 44 mph were recorded at Denver International Airport.

In 2014…a record high min of 45 degrees… broke the previous record of 43 degrees set in 1934…and preceded several days of record cold temperatures from the 11th through the 13th.

» Click here to read the rest of November 5 to November 11: This week in Denver weather history

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October 2017 weather recap: Month offers cooler and wetter than normal conditions

Friday, November 3rd, 2017 4:03pm MST

The month of October certainly saw its fair share of varying temperatures.  We seemed to go back and forth between unseasonably warm to unseasonably cold readings.  The month also brought us our first measurable snow of the season and a good bit of precipitation.

The month started with comfortable readings and dry conditions.  On the 9th of the month though things turned considerably colder and Thornton recorded 4.1 inches of snow.

We immediately rebounded though and warmer weather returned.  A string of 70 plus degree days from the 16th to the 20th were quite nice.  We also stayed dry until the last week of the month.

On the 25th we saw a record-setting high temperature but then 72 hours saw our coldest reading of the month (19.4 degrees).  There again, we bounced back with a warm day on the 29th before finishing up with much colder weather the last two days of the month.  We did see some minimal rain on the 26th and 30th to add to the precipitation total for the month.

Thornton saw an overall average monthly temperature of 48.6 degrees.  This was a good ways below Denver’s long term October average of 50.9 degrees.  Out at DIA where the Mile High City’s official measurements are taken, they were warmer with an average of 50.1 degrees.

Our mercury readings ranged from a high of 84.9 degrees on the 25th down to the 19.4 degree reading on the 27th.  DIA saw similar extremes with a maximum of 84 degrees and a minimum of 13 degrees on those same dates.  The reading of 84 degrees on the 25th was a record high for the date.

In terms of precipitation, Thornton recorded 1.71 inches.  Denver lagged considerably with 0.96 inches for the month.  Those put Thornton well above, Denver just below the October average of 1.02 inches.

Denver averages 4.0 inches of snowfall in October.  Thornton bested that by just a bit with 4.6 inches, the majority of which came on the 9th.  Out at the airport, they could only tally 2.8 inches of the white stuff.

Click here to view Thornton’s October 2017 climate report.

Thornton, Colorado October 2017 temperature summary. (ThorntonWeather.com)

Thornton, Colorado October 2017 temperature summary. (ThorntonWeather.com)

Thornton, Colorado October 2017 precipitation summary. (ThorntonWeather.com)

Thornton, Colorado October 2017 precipitation summary. (ThorntonWeather.com)

From the National Weather Service:

303 AM MDT WED NOV 1  2017




                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
 HIGH              89   10/16/1991
 LOW               -2   10/29/1917
HIGHEST            84   10/25        83       1       86  10/16
LOWEST             13   10/27        22      -9       25  10/20
AVG. MAXIMUM     64.5              65.3    -0.8     74.5
AVG. MINIMUM     35.7              36.6    -0.9     41.2
MEAN             50.1              50.9    -0.8     57.8
DAYS MAX >= 90      0               0.0     0.0        0
DAYS MAX <= 32      0               0.4    -0.4        0
DAYS MIN <= 32     11               8.5     2.5        3
DAYS MIN <= 0       0               0.0     0.0        0

 MAXIMUM         4.17   1969
 MINIMUM            T   1934
TOTALS           0.96              1.02   -0.06     0.26
DAILY AVG.       0.03              0.03    0.00     0.01
DAYS >= .01         5               5.3    -0.3        3
DAYS >= .10         4               2.4     1.6        1
DAYS >= .50         0               0.5    -0.5        0
DAYS >= 1.00        0               0.1    -0.1        0
 24 HR. TOTAL    0.35   10/09 TO 10/09           10/05 TO 10/06

 TOTAL             2.8
TOTALS            2.8               4.0

HEATING TOTAL     455               440      15      231
 SINCE 7/1        585               581       4      310
COOLING TOTAL       1                 5      -4       17
 SINCE 1/1        881               769     112      878

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

AVERAGE WIND SPEED              10.3

AVERAGE SKY COVER           0.50
NUMBER OF DAYS FAIR           11
NUMBER OF DAYS PC             15


THUNDERSTORM              3     MIXED PRECIP               0
HEAVY RAIN                0     RAIN                       1
LIGHT RAIN                8     FREEZING RAIN              1
LT FREEZING RAIN          1     HAIL                       0
HEAVY SNOW                0     SNOW                       4
LIGHT SNOW                4     SLEET                      0
FOG                      10     FOG W/VIS <= 1/4 MILE      5
HAZE                      6

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Thornton’s weekend weather to bring milder temps, some wind

Friday, November 3rd, 2017 5:10am MST

Mother Nature should allow us to warm up a good bit today and tomorrow before returning us to season temps Sunday. The one hiccup along the way will be some breezy winds Saturday.

For today, there is a good bit of moisture and some spots may see some fog early on. After that, look for the clouds to clear and by mid-morning mostly sunny skies will be the rule. Temperatures will warm up to a high in the mid-60s.

Tonight, skies remain mostly clear with lows dipping to 42 degrees.

Saturday will bring even warmer mercury readings but unfortunately with some wind. Mostly sunny skies will be above with downslope winds helping to drive us to highs in the low 70s. The wind will be pretty persistent throughout the day then ease up after dark.

Saturday night into Sunday morning, partly clear skies will be above. Sunday morning lows dip to near the 40 degree mark.

We close out the weekend on Sunday with seasonal temperatures seeing highs in the mid-50s. There will be a decent bit of cloud cover during the day though.

Have a great weekend!

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Thornton’s November 2017 preview: A fall month that can offer up just about anything

Friday, November 3rd, 2017 3:43am MST

Thornton's November weather previewThe weather during the month of November in Denver metro area can offer just about anything.  While it is normally a quiet month, it can be prone to extremes.

November has historically been one of Denver’s snowiest months and major snowstorms are not entirely uncommon.  However conditions can also be quite dry.

Temperatures during the month continue to cool as we get closer to winter and by the end of the month the low temperatures routinely dip to 20 degrees or below.  At times it can in fact bring conditions more like what we see in January.

What lies ahead for November 2017?  Get all the details on November’s weather and what we can expect in our complete preview here.

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Daylight Saving Time to come to an end on Sunday, November 5, 2017

Thursday, November 2nd, 2017 6:00am MST
The United States returns to Standard Time at 2:00am Sunday as Daylight Saving Time comes to an end.

The United States returns to Standard Time at 2:00am Sunday as Daylight Saving Time comes to an end.

The biannual ritual of changing our clocks to adjust for Daylight Saving Time occurs tonight providing yet another signal of the changing of seasons.  The United States will ‘fall back’ one hour at 2:00am Sunday morning as we return to Standard 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.  Others actually like the return to standard time as they get to enjoy an extra hour of sleep.

The time change definitely has big effects on the dawning of daylight and how early it gets dark in the evening.

Sunrise on Saturday occurs at 7:32am but on Sunday it will be at 6:33am. Similarly, sunset will occur at 5:54pm on Saturday but on Sunday the sun will disappear over the horizon at 4:53pm.

For many this means that when they get home from work it will now be dark and outdoor activities will be significantly curtailed as a result.

Arizona and Hawaii are the only states that do not observe Daylight Saving Time and remain on Standard Time year round.    The U.S. territories of Puerto Rico, American Samoa, Guam, Northern Mariana Islands, and the United States Virgin Islands also do not observe the event.

It won’t be all that long though before Daylight Saving Time returns.  On March 11, 2018 we will ‘spring forward.’

Daylight Saving Time Schedule

The mandated beginning and end of Daylight Saving Time has changed in the United States over the years.

The most recent schedule was set by the Energy Policy Act of 2005 and took effect in 2007.  We now ‘spring forward’ to begin Daylight Saving Time on the second Sunday in March and ‘fall back’ with the return to Standard Time on the first Sunday in November.

Year DST Begins 2 a.m.
(Second Sunday in March)
DST Ends 2 a.m.
(First Sunday in November)
2017 12 March 2017 5 November 2017
2018 11 March 2018 4 November 2018
2019 10 March 2019 3 November 2019
2020 8 March 2020 1 November 2020
2021 14 March 2021 7 November 2021
2022 13 March 2022 6 November 2022
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Thursday to offer warmer than normal temps, less wind

Thursday, November 2nd, 2017 5:24am MST

Today we get a break from all that wind that we saw yesterday. Temperatures will be warmer than normal but with a good bit of cloud cover.

Partly sunny skies start things off and we will see a pretty consistent level of cloud coverage throughout the day. Some sun will peek through occasionally. Temperatures start out chilly and will take a while to start warming up. Once they do, we should be on our way to a high in the low to mid-60s but those clouds may inhibit the highs a bit. Overall conditions will be dry and calm.

Tonight, skies will clear some and lows will dip to around 40 degrees.

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Very mild temps, windy conditions for Wednesday

Wednesday, November 1st, 2017 5:00am MST

If you just looked at the temperature forecast for today you might be pleased. However, while it will be quite warm, we are also going to see a healthy dose of wind that will dampen that enthusiasm.

The day starts with partly sunny skies and overall we should see those same conditions above throughout the day. The wind will be the main focus with speeds in increasing through the morning hours and peaking in the afternoon. Gusts to 45 mph or so will be possible at points. The downslope winds will help us be quite warm today with highs reaching the mid-70s.

This evening the winds should ease quickly and be calm overnight. Low temperatures into tomorrow morning will bottom out around 40 degrees under mostly cloudy skies.

Keep an eye on those windspeeds here.

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