Thornton, Colorado, USA
UpdatedTue, 03-Oct-2023 12:10pm MDT 


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After a little bit of a damp start, Thornton’s weekend to end up very pleasant

Friday, September 15th, 2023 4:59am MDT

Following yesterday’s deluge, today we remain a bit cool and damp. However, the balance of the weekend will be very nice with lots of sun.

For today, we will have some clouds this morning then gradual clearing will be seen in the afternoon. A few sprinkles can be expected this morning then this afternoon there will be a slight chance for a thunderstorm. Highs will top out in the upper 60s. Tonight, skies will clear and lows will dip into the upper 40s.

Saturday turns things around in fantastic fashion. You will be hard pressed to find a cloud at all during the day and conditions will be calm and dry. Look for highs in the mid to upper 70s. Saturday night skies remain clear and lows will drop to around 50 degrees.

Sunday continues the nice weather with even warmer temperatures. Highs will be in the low to mid-80s with sunny skies above. The late afternoon will bring some breezy winds but otherwise it will be calm and pleasant.

Have a great weekend!

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Cooler temps, showers and thunderstorms for Thornton’s Thursday

Thursday, September 14th, 2023 4:59am MDT

A couple cold fronts will be moving through today and with them, temps cool and we stand a good chance to see some precipitation.

As the first front passes this morning, cloud cover will increase with partly sunny skies for the morning then coverage will gradually increase. High temperatures will top out in the low to mid-70s.

That warming should be enough to get some convection going and help stir things up for showers and thunderstorms. The afternoon will see some scattered activity with increasing coverage late afternoon into early evening.

This evening, showers will become widespread and we should see some good numbers from then through about midnight. After midnight, showers will ease. Overnight lows tonight will be around the 50 degree mark.

Our live radar is the spot to watch for the showers and thunderstorms.

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Wednesday offers up temps near normal, just a slight chance for a PM storm

Wednesday, September 13th, 2023 4:57am MDT

A pretty nice day ahead for Thornton. We will see some cloud cover but temps will be near average and there is only a sight chance for a thunderstorm.

Partly sunny skies start us off and will continue throughout the daytime hours. High temperatures will be topping out right near the 80 degree mark. Late afternoon we begin to see just a slight chance for a thunderstorm.

Tonight, the evening may see a storm then after dark skies will be partly clear. Overnight lows will be in the low 50s.

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Tuesday in Thornton dries out, warms up

Tuesday, September 12th, 2023 5:25am MDT

Following yesterday’s cool and somewhat damp weather, we look to remain dry today and see temps get warmer but remain below average.

Sunny to mostly sunny skies will be above during the daytime hours. Overall conditions will be calm and dry other than some slightly breezy winds in the late afternoon and evening. Look for highs to top out in the upper 70s.

Tonight, lows will dip to around 50 degrees under partly cloudy skies.

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Cool temperatures, light showers start off Thornton’s workweek

Monday, September 11th, 2023 5:09am MDT

As of this writing, we have received a welcome 0.34 inches of rainfall, something we have been lacking in recent weeks. Today we will add some light amounts to that and remain much cooler than normal.

Cloudy skies start us off and will be with us this morning. The afternoon should offer up some clearing. Correspondingly, light rain / sprinkles will be seen these morning then decrease in the afternoon. Highs will top out in the mid-60s, well below the average high for the date of 81 degrees.

Tonight, cloud cover will continue to decrease and shower chances will end by about 9:00pm. Overnight lows will dip to around 50 degrees.

Please take time today, Patriot Day, to remember the men and women who gave their lives 22 years ago today. Say a prayer for them, those they left behind, and all who served and sacrificed to bring justice to those who attacked us on 9/11.

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September 10 to September 16: This week in Denver weather history

Sunday, September 10th, 2023 5:10am MDT

This Week in Denver Weather History

Severe weather is less common as we enter the fall season but it is not entirely unheard of. As we see in our look back at this week in Denver weather history, we have seen everything ranging from torrential rains to tornadoes and even heavy snow.


In 2020…a worsening drought that started in the spring and continued through September. Outside of an early season snow on the 8th…the month of September was another unseasonably warm and dry period. The combination of hot…mostly dry conditions…and critically dry fuels… resulted in a continuation and rapid expansion of several massive wildfires. The Cameron Peak fire…which became the largest in the state`s history started on August 13th…and continued through September. As a result…very poor air quality continued to impact Denver and the entire Front Range. Denver recorded the most days ever with a high temperature of 90 degrees or better; 75 days. The last of which was 91 degrees on the 24th. The previous record was 73 days set in 2012.


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 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.


In 2018…the high temperature equaled or exceeded 90 degrees for 8 consecutive days; breaking the previous streak of 7 consecutive days in the month of September.


In 2018…the high temperature equaled or exceeded 90 degrees for 9 consecutive days; marking the first time such an occurrence has taken place in the month of September. It also brought September of 2018 into a 4-way tie for most 90 degree + days in the month. Previous years included 2017…2005 and 1895. During the streak…4 record high temperatures were either tied or broken…and one record high minimum temperatures was broken.


In 1910…west winds were sustained to 42 mph.

In 1951…a vigorous Canadian cold front produced a dust storm across metro Denver. Northeast wind gusts to 43 mph reduced the visibility at Stapleton Airport to as low as 1 1/2 miles for nearly 5 hours. The temperature dropped 47 degrees in 8 hours…from a high of 92 degrees to a low of 45 degrees.

In 1967…a microburst wind gust to 52 mph produced blowing dust and briefly reduced the visibility to 1/2 mile at Stapleton International Airport.

In 1974…a trace of snow…the first of the season…ended the shortest period without snow…94 days from June 9th through September 10th. A trace of snow also fell on June 8th.

In 1995…strong post-frontal winds associated with a fast moving pacific cold front knocked down power poles and trees as it moved through metro Denver. Numerous power outages affected nearly one thousand people in Denver and Jefferson counties. West winds gusted to 34 mph at Denver International Airport.


In 2013…a deep southerly flow over Colorado… Ahead of a nearly stationary low pressure system over the great basin… Pumped copious amounts of monsoonal moisture into the area. In addition…a weak stationary front stretched along the Front Range foothills and Palmer Divide.  This resulted in a prolonged period of moderate to heavy rain across the Front Range foothills…Palmer Divide…urban corridor. By the 14th…storm totals ranged from 6 to 18 inches… Highest in the foothills of Boulder County. The headwaters then moved down the South Platte River and caused widespread flooding with record flood stages at several locations as it made its way downstream.  The record high flood stages resulted in widespread flooding along the South Platte River basin. The flood damage encompassed 4500 square miles of the Front Range…left 7 dead… Forced thousands to evacuate…and destroyed thousands of homes and farms. Record amounts of rainfall generated flash floods that tore up roads and lines of communication… Leaving many stranded. Nearly 19000 homes were damaged… And over 1500 destroyed. Colorado department of transportation estimated at least 30 state highway bridges were destroyed and an additional 20 seriously damaged. Preliminary assessments of the state`s infrastructure showed damage of $40 million to roads and $112 million to bridges. Repair costs for state and county roads ran into the hundreds of millions of dollars. Miles of freight and passenger rail lines were washed out or submerged… Including a section servicing Amtrak`s iconic California Zephyr. The town of Lyons was isolated by the flooding of St. Vrain creek…and several earth dams along the Front Range burst or were over-topped. Floodwaters swept through Estes Park; damaged hundreds of buildings and destroyed large sections of U.S. 34 from Loveland and U.S. 36 from Lyons to Boulder. U.S. 34 suffered the most damage… With 85 percent of its roadway and bridges destroyed. In Weld County…about nearly two thousand gas wells were damaged and had to be closed off as the floodwaters inundated entire communities. Sewage treatment plants and other utilities were knocked out in a number of towns. Governor Hickenlooper declared a disaster emergency on September 13th…in 11 counties across northeast Colorado including:  Adams…Arapahoe…Broomfield…Boulder…Denver…  Jefferson…Larimer…Logan…Morgan… Washington and Weld. By the 15th…federal emergency declarations covered those counties as well as Clear Creek County. Projected losses from the flooding statewide was nearly two billion dollars in property damage…according to Eqecat… A catastrophe modeling firm.  The damage was most severe in and around Lyons and Boulder.  More than 11 thousand people were evacuated…reportedly the largest since Hurricane Katrina. President Obama declared a state of emergency for Boulder and Larimer counties.  An additional 10 counties were added on the 16th and included: Adams… Arapahoe…Broomfield…Clear Creek…Denver…Jefferson…  Morgan…Logan… Washington and Weld counties. The president also declared a major disaster specifically for Boulder County.  There were six fatalities directly attributed to flash flooding. Two 19-yr old teenagers died on the 11th…after they were swept away by floodwaters after abandoning their car on Lindon Drive in Boulder. In Jamestown…a 72-yr old man was killed when the building he was in collapsed. An 80-yr old Lyons resident died in the early morning hours of the 12th…when his truck was swept into the St. Vrain River near his home. Later on the 12th…a 79-yr old Larimer County resident was killed when she was swept away while trying to climb to safety from her home in Cedar Point. A 61-yr old cedar point resident died when her home was swept down the Big Thompson River by the floodwaters. An 80-yr old Idaho Springs resident drowned in Clear Creek when the embankment he was standing on collapsed. In Boulder…some of the monthly records broken included: one-day all-time record: 9.08 inches which shattered the previous wettest day of 4.8 inches set on July 31… 1919; one-month record of 18.16 inches…which broke the previous all-time monthly record of 9.59 inches set in May of 1995; wettest September on record which broke the previous record of 5.5 inches set in September of 1940; one-year record of 34.15 inches broke the previous wettest year of 29.93 inches set in 1995. At Denver International Airport…the total precipitation for the month of September was 5.61 inches…which was 4.65 inches above the normal of 0.96 inches. This is the most precipitation ever recorded in Denver for the month of September. Daily precipitation records included 1.11 inches on the 12th and 2.01 inches on the 14th.


In 1974…post-frontal rain changed to snow overnight for the first snow of the season. Snowfall totaled only 1.8 inches at Stapleton International Airport where north winds gusted to 40 mph on the 11th. High temperature of only 46 degrees on the 12th set a new record low maximum for the date. » Click here to read the rest of September 10 to September 16: This week in Denver weather history

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Thornton’s weekend starts out mild and dry, will end cool and wet

Friday, September 8th, 2023 4:50am MDT

A pretty nice weekend on tap. Things start off with more of the same mild, dry conditions of recent days. It will end with a turn toward cooler temperatures and a good chance for some much-needed precipitation.

For Friday, it is a virtual clone of what we saw this week. Lots of sun above and highs will top out around the 90 degree mark. There will be some breezy winds this afternoon. Tonight, lows will dip to the mid-50s under mostly clear skies.

The daytime hours Saturday offer more of the same. Highs will be in the upper 80s under sunny skies and with some breezy PM winds. Saturday evening and overnight into Sunday, there is a slight chance for some showers and thunderstorms.

Sunday morning, the ridge finally breaks down as a cold front moves in. This will usher in some noticeable changes that will last well into next week. For Sunday, skies will be mostly cloudy with highs in the low 70s. The morning may bring a sprinkle of rain and then in the afternoon and evening, shower and thunderstorm activity will increase with the potential for a nice shot of precipitation.

Have a great weekend!

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Thursday in Thornton to be a bit toasty, remains calm and dry

Thursday, September 7th, 2023 4:52am MDT

Little change in the warmer-than-normal weather pattern we have been experiencing. Today offers more of the same with mercury readings climbing a degree or two.

Sunny skies will be the general rule other than some mid-morning clouds that won’t last long. Overall, conditions will be calm and dry. High temperatures will be topping out in the low 90s.

Tonight, lows will dip to the mid-50s under mostly clear skies.

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Temps rebound to above average levels Wednesday with lots of sun

Wednesday, September 6th, 2023 5:04am MDT

Our brief cool-down yesterday is gone and we now return to above normal temps for a few days. The latter part of the coming weekend and early next week should bring some relief.

For today, look for sunny skies without a cloud until the late afternoon. Overall conditions will be calm and dry as we head for a high in the mid to upper 80s.

Tonight, skies remain clear with lows in the mid-50s.

Looking ahead, we do foresee a series of cold fronts arriving Sunday and into early next week. These should allow for an increase in moisture and a decrease in temperatures. More in our extended forecast here.

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Tuesday in Thornton to offer up pleasant, calm conditions

Tuesday, September 5th, 2023 5:00am MDT

A bit of a break from the heat to start the abbreviated workweek. Temps will be a bit below normal (finally!) and it will be calm and dry.

Sunny skies will be above throughout with only a few clouds appearing in the late afternoon. Overall conditions will be calm with some slightly breezy winds. High temperatures will top out around the 80 degree mark.

Tonight, skies will remain clear and conditions calm. Overnight lows will be in the low 50s. Enjoy!

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