Thornton, Colorado, USA
UpdatedThu, 12-Dec-2019 4:45am MST 


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Thornton’s weekend to feature warming temperatures, calm, dry conditions

Friday, September 13th, 2019 4:54am MST

Mother Nature isn’t quite ready to let summer go. We will start out with seasonal temps but by the end of the weekend, we will again be pushing toward the 90 degree mark.

For Friday, sunny skies will be above throughout the day. Conditions will be calm and dry. Highs today will be around the 80 degree mark, average for the date. Tonight, skies will remain clear with lows in the low 50s.

Saturday looks much like today but with warmer temperatures. Sunny skies and calm conditions can be expected. High temperatures will be in the mid-80s. Overnight Saturday into Sunday morning, clear skies will be above with lows in the mid-50s.

The weekend closes out with some clouds but also the warmest temperatures of the period. Look for mostly sunny skies with highs near 90 degrees.

Have a great weekend!

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Thornton’s Thursday to feature lots of sun, temperatures a bit cooler than normal

Thursday, September 12th, 2019 4:57am MST

We are set to enjoy a very nice, late fall day today. Sunny skies will be above and temps will be quite comfortable.

Clear skies start us off and will be with us through the day. A few clouds may appear here and there but won’t amount to much. High temperatures today will top out in the mid-70s, about five degrees below normal.

Tonight, skies will be clear with lows near the 50 degree mark.

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Wednesday offers slightly cooler temperatures, slight chance for storms

Wednesday, September 11th, 2019 5:13am MST

A good looking late summer day for Thornton. Temperatures will top out within a few degrees of average for the date and we have just a bit of a chance for a PM storm.

Mostly sunny skies starts us off and will be with us throughout the day. Highs will top out in the low to mid-80s, a bit above the average high for the date of 81 degrees.

The afternoon will see some scattered thunderstorms move off the foothills and to lower elevations. Most activity however will be to our northeast.

Tonight, any storms will end by midnight and skies will clear. Overnight lows will be in the low 50s.

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September 8 to September 14: This Week in Denver Weather History

Tuesday, September 10th, 2019 2:59pm MST
This week in Denver weather history

September 8 to September 14: This Week in Denver Weather History

Our look back at this week in Denver weather history has stories of extremes from early season snowfall to wildfires to dangerous lightning and flooding.

From the National Weather Service:


In 1988…layers of smoke aloft from large forest fires in Yellowstone National Park completely obliterated the sun at times. At Stapleton International Airport…surface visibility was reduced at times to 5 and 6 miles in smoke.


In 2010…the Fourmile Canyon wildfire…northwest of Boulder… Broke out on the morning of the 5th. It originated from an unattended fire pit at a local residence. The wildfire quickly consumed 5 1/2 square miles or 3500 acres the first day…and forced the evacuation of over three thousand residents. Erratic 45-mph gusts sent the fire in two directions at times. Very dry weather conditions preceded the fire. The combination of strong winds…low relative humidities and dry fuels allowed the wildfire spread rapidly through the steep…heavily forested terrain. The flames were reportedly 20 to 50 feet in length. Towns within the burn area included Salina…Wallstreet and Gold Hill. The dry conditions coupled with gusty winds ranging from 45 to 64 mph persisted for several more days. Fire managers used as many as 700 firefighters and support personnel from 35 agencies and seven air tankers to battle the wildfire. A total of 6181 square acres or approximately 10 square miles were burned. The Fourmile Canyon wildfire was the most destructive fire in Colorado history in terms of the damage to personal property. It destroyed 171 homes with an estimated cost of 217 million dollars.


In 1884…a windstorm from mid-afternoon until the early morning hours of the 8th produced south winds sustained to 48 mph. The strong winds toppled several trees in the city.

In 1892…there was a trace of rainfall each day. This together with a trace of rain on both the 2nd and 3rd was the only rainfall of the month…making the month the driest on record. The record was equaled in 1944.


In 1886…the last thunderstorm of the season pelted the city with hail the size of beans and dropped 0.81 inch of precipitation.

In 1962…the earliest first freeze of the season occurred. The temperature dipped to a low of 31 degrees.

In 1973…hail up to 1 1/2 inches in diameter fell northeast of Boulder. A tornado was reported by a pilot east of Parker. No damage was reported.


In 1933…heavy rain in the foothills over the clear creek and Golden Gate Canyon watersheds caused flooding in Golden and damaged the roadway in Golden Gate Canyon… Which resulted in its closure.

In 1969…a funnel cloud was sighted in southeast Denver. There was also considerable thunderstorm activity and local heavy rain across metro Denver. Rainfall totaled 1.30 inches at Stapleton International Airport where small hail also fell.

In 1973…hail from 3/4 inch to 1 3/4 inches in diameter fell in Westminster and south of Broomfield.

In 2009…a man was critically injured when he was struck by lightning while riding his bicycle. He was nearing a paramedic van when he was hit. His heart stopped but paramedics quickly responded and were able to resuscitate him.

In 2011…a man was struck by lightning at the Adams County fairgrounds. He was leaning against a tree while watching a cross country meet when the tree was hit. The lightning traveled down the tree and up through the ground…using him as a conductor. The victim received second and third degree burns.


In 1933…heavy rain over the Cherry Creek…Plum Creek…Big Dry Creek…and Little Dry Creek watersheds caused flooding on the South Platte River in Denver overnight. Nearly an inch of rain…0.98 inch…fell in the city.

In 1944…a trace of rain fell on each day. This together with a trace of rain on the 4th and 30th was the only precipitation for the month. The total of a trace of precipitation for the month equaled the driest September on record first set in 1892.

In 1994…unusually very warm weather resulted in three temperature records being equaled. High temperatures of 94 degrees on the 9th and 93 degrees on the 10th equaled record maximums for the dates. Low temperature of 63 degrees on the 9th equaled the record high minimum for the date.


In 1985…golf ball size hail was reported just east of Parker.

In 1989…3/4 inch diameter hail fell in Littleton. Heavy rain produced local flooding in Lakewood. The heavy rain caused the wall of a house to collapse.

In 1993…thunderstorm winds downed power lines…which caused a power outage in Castle Rock.

» Click here to read the rest of September 8 to September 14: This Week in Denver Weather History

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Tuesday’s temps increase, slight chance for a PM thunderstorm

Tuesday, September 10th, 2019 7:06am MST

A pretty good looking day ahead for Thornton. We’ll see a good bit of sun, temps above normal and just a bit of a chance for a storm.

Mostly sunny skies start us off and will be with us for much of the day. The afternoon will see a typical increase in clouds. Today’s high temperature will hit around 87 degrees, about 6 degrees above normal.

After noon, a few, scattered thunderstorms are expected and we will see at least a bit of a chance for a storm through the evening.

Tonight, any thunderstorms should end by midnight and skies will clear. Overnight low temps will be in the mid-50s.

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Thornton’s workweek starts off with calm conditions, temps a bit above normal

Monday, September 9th, 2019 4:54am MST

After finally receiving some much-needed rain yesterday, today dries out and warms up a bit.

Partly clear skies with some areas of patchy fog will be seen early. The fog will burn off soon after sunrise and we will then enjoy sunny skies with only a few clouds here and there after that.

High temperatures today will be in the mid-80s, a bit above the average high for the date of 81 degrees. At this time, we don’t expect to see any thunderstorm activity.

Tonight, lows will be in the mid-50s and skies will remain mostly clear.

The rest of the week will see overall pleasant conditions, a couple chances for storms and temps on most days running a bit above normal. See the extended weather forecast here.

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Thornton’s weekend to see temps close to normal, good chances for storms

Friday, September 6th, 2019 6:06am MST

We get a break from the heat for the three-day period – finally. Perhaps best of all, we do see a decent chance for thunderstorms, particularly today and Sunday.

For today, partly sunny skies will be above. A few sprinkles may fall this morning and then thunderstorms are expected this afternoon, mainly after 3:00pm. Highs will be around 83 degrees. Tonight, storm activity will end by midnight and skies will see some clearing. Overnight lows will be around 60 degrees.

Saturday will be the warmest day of the weekend with highs in the mid to upper 80s. Mostly sunny skies will be above and scattered thunderstorms may be expected in the afternoon. Saturday night into Sunday morning, skies will clear and lows will be in the upper 50s.

Sunday will offer mostly sunny skies and highs in the mid-80s. Showers and thunderstorms are expected, mainly in the afternoon. Have a great weekend!

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Denver sets record high temperature for September 5, third high temp record of the month

Thursday, September 5th, 2019 6:36pm MST

Record High TemperaturesOnly five days into the month of September and the heat has records falling left and right.

Today, at 2:05pm, the temperature at Denver International Airport where Denver’s official readings are taken, reached 98 degrees. This topped the previous record high for September 5 of 97 degrees set in 2013 and 1899.

Here in Thornton we were actually warmer with a high of 99 degrees coming at 2:58pm.

Today’s record comes on the heels of record highs on the 1st and the 2nd of the month.

The 100 degree high of the 2nd was also the latest 100 degree reading ever recorded in Denver and also the warmest September temperature on record.

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Thornton’s Thursday sees the heat return, offers a chance for late day thunderstorms

Thursday, September 5th, 2019 4:52am MST

Back to the 90s for us again today as temperatures climb well above normal. We do have a chance to see a thunderstorm, mainly in the evening.

Mostly sunny skies start us off and will be with us until the afternoon when cloud cover will increase. Highs will be in the low to mid-90s.

We’ll see a chance for thunderstorms after 4:00pm with the best opportunity coming from about 7:00pm to 9:00pm.

Any storm activity should end by midnight leaving us with partly clear skies overnight and lows to the low 60s.

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August 2019 weather recap: Thornton experiences very warm, very dry month

Wednesday, September 4th, 2019 9:31am MST

The month of August usually brings respectable amounts of precipitation and by the latter part of the month, cooler temperatures. Mother Nature however had other plans last month keeping the heat on and the moisture at bay.

A dry, westerly flow was dominant for much of the month. While there were a few cool fronts and PM thunderstorms, these failed to amount to much at all and were a rarity.

Thornton saw 21 days of 90 degree or higher readings during the month. Only five days saw precipitation and three of those were in virtually negligible amounts.

Thornton’s overall average temperature for the month was 73.9 degrees. This makes it the warmest August since ThorntonWeather.com came online 13 years ago. The reading was a good ways above the long-term Denver average for the month of 72.5 degrees.

At DIA, where Denver’s official temperatures are recorded, it was even warmer with an average of 75.4 degrees. This put August 2019 into the books tying August 2007 as the warmest August ever recorded in the Mile High City.

One temperature record was set in Denver during the month when on the 19th, the high temperature topped out at 99 degrees. This topped the old record high for the date of 97 degrees.

In terms of precipitation, Denver averages 1.69 inches during the month of August. This year, Thornton recorded a paltry 0.18 inch during the month. Denver fared a bit better with 0.58 inches. Both were clearly far short of average and Thornton’s was the least amount of precipitation received in August since ThorntonWeather.com came online 13 years ago.

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

Thornton, Colorado's August 2019 temperature summary. (ThorntonWeather.com)

Thornton, Colorado’s August 2019 temperature summary. (ThorntonWeather.com)

Thornton, Colorado's August 2019 precipitation summary. (ThorntonWeather.com)

Thornton, Colorado’s August 2019 precipitation summary. (ThorntonWeather.com)

Thornton, Colorado's August 2019 weather summary. (ThorntonWeather.com)

Thornton, Colorado’s August 2019 weather summary. (ThorntonWeather.com)

910 AM MDT SUN SEP 1 2019




                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
 HIGH             105   08/08/1878
 LOW               40   08/26/1910

HIGHEST            99   08/19
LOWEST             51   08/28

AVG. MAXIMUM     90.5              87.2     3.3     86.8
AVG. MINIMUM     60.2              57.9     2.3     58.0
MEAN             75.4              72.5     2.9     72.4
DAYS MAX >= 90     18              11.5     6.5       11
DAYS MAX <= 32      0               0.0     0.0        0
DAYS MIN <= 32      0               0.0     0.0        0
DAYS MIN <= 0 0 0.0 0.0 0 
 MINIMUM 0.02 1924 
TOTALS 0.58 1.69 -1.11 0.93 
DAILY AVG. 0.02 0.05 -0.03 0.03 
DAYS >= .01         3               8.6    -5.6        7
DAYS >= .10         1               4.3    -3.3        2
DAYS >= .50         0               1.2    -1.2        0
DAYS >= 1.00        0               0.3    -0.3        0
 24 HR. TOTAL    0.46   08/08 TO 08/08           08/14 TO 08/14

TOTALS            0.0               0.0

HEATING TOTAL       0                10     -10        9
 SINCE 7/1          0                16     -16        9
COOLING TOTAL     326               244      82      247
 SINCE 1/1        757               688      69      862

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

AVERAGE WIND SPEED              9.3

AVERAGE SKY COVER           0.50
NUMBER OF DAYS FAIR            9
NUMBER OF DAYS PC             21


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