Thornton, Colorado, USA
UpdatedSun, 18-Feb-2018 3:45am MST 


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Thornton’s Tuesday brings very warm temps, high fire danger

Tuesday, September 19th, 2017 5:03am MST

Our temperatures rebound today and climb to about 10 degrees above normal. More notable, will be high fire danger brought on by gusty winds and low humidity.

We start the day with sunny skies and other than a few clouds in the afternoon, the view will be largely unobstructed. Temperatures start out cool but then will begin a steady climb with highs in the mid to upper 80s, well above the average of 77 degrees for today.

An approaching trough is going to bring on gusty winds by late morning that will last into the evening. Coupled with low humidity and tinder dry fuels, the fire danger is very high.

The National Weather Service has issued a Red Flag Warning that is in effect from 11:00am to 8:00pm. Any fires that do get started could see rapid growth and extreme fire behavior. Please be very careful!  Read the complete text of the warning here.

Winds will die down tonight with skies remaining mostly clear. Lows will be dipping to around 50 degrees.

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September 17 to September 23: This week in Denver weather history

Monday, September 18th, 2017 5:02am MST
This Week In Denver Weather History

September 17 to September 23: This week in Denver weather history

The calendar may still say it is summer for a few more days but our look back at this week in Denver weather history shows that Old Man Winter can still make an appearance.

From the National Weather Service:


In 2000…unusually hot weather for so late in the season occurred when temperatures climbed into the 90’s setting daily record maximum temperatures on each of the 3 days. The high temperature was 92 degrees on the 15th and 95 degrees on both the 16th and 17th.


In 1906…rain on 5 consecutive days totaled 1.61 inches. A thunderstorm occurred on the 17th. High temperatures ranged from 48 degrees on the 16th to 65 degrees on the 15th. Low temperatures were in the lower to mid 40’s.


In 1971…a record breaking early fall snow storm caused extensive damage to trees and utility lines. The heavy wet snow occurred with little wind…but caused record breaking cold temperatures for so early in the season. Snowfall totaled 15.6 inches at Stapleton International Airport with most of the snowfall…12.0 inches…occurring on the 17th. This was the heaviest first snow of the season. The maximum snow depth on the ground was 13 inches. Record low temperatures were set on three consecutive days: 31 degrees on the 17th…23 degrees on the 18th…and 20 degrees on the 19th…which was also a new all-time record minimum for the month at that time. Record low maximum temperatures were set on 4 consecutive days: 48 degrees on the 16th…35 degrees on the 17th…40 degrees on the 18th… And 42 degrees on the 19th.


In 1873…brisk west to northwest winds at different times during the day…generally in sudden gusts…spread a good deal of dust into the city.

In 1953…strong winds caused thousands of dollars in damage to Boulder. The winds blew for most of the day with great gustiness…and a freak twister was reported during the afternoon. Damage was minor. A thunderstorm wind gust to 40 mph caused some blowing dust at Stapleton Airport.

In 1992…a tornado touched down briefly near Bennett. No damage was reported.

In 1993…severe thunderstorms rumbled across northern portions of metro Denver. Hail as large as 1 3/4 inches in diameter fell in Brighton. Dime size hail damaged several roofs of residences in Lafayette.

In 2000…for the second day in a row…the high temperature of 95 degrees at Denver International Airport broke three record temperature extremes: the high temperature broke the previous record for the day of 94 degrees set in 1895; it marked the warmest it has been for so late in the season; it also marked the 61st day in the year that the temperature had equaled or exceeded 90 degrees…eclipsing the record equaled the previous day and first set on September 29… 1994.


In 1901…northeast winds were sustained to 42 mph with gusts to 50 mph behind an apparent cold front.

In 1948…the low temperature cooled to only 69 degrees…the all-time record high minimum for the month.

In 1988…a strong cold front blasted metro Denver with high winds. Gusts reached 82 mph in Longmont and 81 mph at Jefferson County Airport near Broomfield where the winds flipped over and destroyed a small airplane. Wind gusts to 60 mph were recorded in Boulder and Wheat Ridge. West wind gusts to 54 mph were clocked at Stapleton International Airport. The strong winds downed trees and power lines and damaged homes and cars. A Longmont man was slightly injured…when a tree fell on top of his car.

In 1990…a slow moving thunderstorm over southwest metro Denver spawned an ominous looking funnel cloud near the intersection of Sheridan Blvd. and U.S. Highway 285. The funnel cloud nearly touched down a few times before lifting back into the main cloud. No damage was reported. Pea to marble size hail and 3/4 inch of rain fell over central and northeast Denver. Numerous streets and underpasses became flooded on Denver’s south side when the heavy runoff backed up storm sewers. Thunderstorm rainfall totaled 1.02 inches at Stapleton International Airport.

In 1993…a severe thunderstorm rolled through southeast metro Denver. Dime size hail was reported in many areas. Straight-line winds from the thunderstorm…measured by a weather spotter at 70 mph…tore the roof off 6 apartments of an apartment complex in Aurora. Heavy rain which accompanied the winds caused major damage to the apartments as well as the contents. Many trees…fences… And power poles were knocked down by the strong winds. Heavy rain flooded roadways in Denver and Aurora. Thunderstorm rainfall totaled 1.08 inches and north winds gusted to 44 mph at Stapleton International Airport where the visibility was briefly reduced to as low as 1/4 mile in heavy rain.

In 1996…a late summer snowstorm struck the northern mountains and Front Range eastern foothills. Golden Gate Canyon received 6 inches of new snow with 5 inches reported at both Nederland and Blackhawk. Thunderstorms produced heavy rain across metro Denver…which was mixed with snow by late evening. Rainfall totaled 0.83 inch at the site of the former Stapleton International Airport and 1.22 inches at Denver International Airport where northwest winds gusted to 39 mph.


In 1955…heavy rains caused flash flooding across portions of metro Denver. Rainfall totaled 1.71 inches at Stapleton Airport.


In 1955…hail stones to 2 1/2 inches in diameter were reported north of Denver. The large stones broke many automobile windshields.

In 1963…hail to 3/4 inch in diameter fell in Westminster.

In 1983…an unusually strong cold front roared through metro Denver during the afternoon hours. At Stapleton International Airport…the temperature dropped 51 degrees… From a sunny 86 degrees to a snowy 35 degrees…in just 7 hours. Strong winds and a wall of blowing dust followed the front. Northeast winds gusting to 36 mph briefly reduced the surface visibility to 1 mile in blowing dust at Stapleton International Airport where only a trace of snow fell later.

In 1996…high winds gusting to 84 mph were measured at Golden Gate Canyon in the foothills west of Denver. West winds gusted to only 25 mph at Denver International Airport.

20 » Click here to read the rest of September 17 to September 23: This week in Denver weather history

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Monday brings lots of sun, warmer temperatures to Thornton

Monday, September 18th, 2017 4:58am MST

The cooler, unsettled weather of this past weekend has moved out and we will warm right back up today. In fact, we’ll see above normal temperatures until the end of the week when things look to cool down quite a bit again.

For today sunny skies start things off and will dominate most of the day. This afternoon we will see a few more clouds but nothing intrusive. Overall conditions will be dry and calm. Highs today will top out in the mid-80s, a good bit above the average of 78 degrees for the date.

Tonight mostly clear skies will be above with lows in the low 50s.

For the balance of the week, look for above normal temperatures through Thursday. Friday will cool to near normal then this weekend a cold front arrives cooling things down quite a bit. Get the details in the extended forecast here.

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Thornton’s weekend weather brings relief from the recent heat

Friday, September 15th, 2017 5:11am MST

We are finally set to break out of our recent pattern of unseasonably weather, at least for a few days. A series of disturbances will bring temperatures down but only offer up slight chances for precipitation.

Your Friday looks to be a rather pleasant and mild day. Look for plenty of sun above as we head for a high temperature in the low to mid-80s. While still warmer than normal, it is a nice break from the 90s. This evening cloud cover will increase and there is a slight chance for a sprinkle of rain after dark. Around that same time, winds are expected to be gusty as a cold front moves in. Lows Saturday night into Sunday morning will dip into the mid to upper 40s.

Saturday will be cooler but also a good bit cloudier. Look for partly sunny skies above throughout the day. Highs will be in the low to mid-70s. The evening may bring a rain shower through. Overnight Saturday skies will be partly clear and lows in the mid to upper 40s.

Sunday is going to see temperatures rebound a bit. Highs will be in the mid-70s under mostly sunny skies. If we can get warm enough to get convection going, the afternoon and evening may bring a thunderstorm or two.

Have a great weekend!

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

Thursday, September 14th, 2017 5:13am MST
This Week In Denver Weather History

September 10 to September 16: 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 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 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.


In 1887…west winds to 42 mph were recorded in the city.

In 1952…a thunderstorm outflow produced strong southeast winds gusting to 52 mph. Surface visibility at Stapleton Airport was briefly reduced to 2 miles in blowing dust.

In 1963…a nearly stationary…white tornado near Bennett was sighted from Denver. No damage was reported.

In 1989…an early snowfall and the first of the season brought 2 to 3 inches of slush to metro Denver. More snow whitened the foothills west of Denver where 6 inches were measured at Evergreen. The snow fell on leaf laden trees… And sagging branches onto power lines caused outages. Much of Denver’s snow fell during the evening rush hour…creating traffic chaos. Snowfall totaled 2.3 inches at Stapleton International Airport where the maximum snow depth on the ground was only 1 inch due to melting.

In 1994…thunderstorm microburst winds gusted to 67 mph in Boulder. No damage was reported.

In 2002…a severe thunderstorm produced hail as large as 1 inch in diameter near Castle Rock.

» Click here to read the rest of September 10 to September 16: This week in Denver weather history

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Thornton’s Thursday brings better chance for storms, slightly cooler temps

Thursday, September 14th, 2017 4:58am MST

An approaching disturbance is going to mix things up just slightly today. Temperatures are going to cool a few degrees and we stand better chances of seeing some afternoon and evening storm activity.

The day starts with mostly sunny skies that will last until the early afternoon. Cloud cover will then increase from the afternoon into tonight. Temperatures will be topping out around 88 degrees, still much warmer than average but at least a bit cooler than recent highs.

Isolated thunderstorm activity will be possible this afternoon, particularly from about 4:00pm to 6:00pm. Gusty winds will be the most notable feature of any storms along with a chance for some brief, moderate rain. Storms will die off after dark and then tonight we will see lows in the mid-50s.

Keep an eye out for the storms with our interactive radar here.

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Wednesday continues unseasonably warm temps, brings slight chance for storms

Wednesday, September 13th, 2017 4:59am MST

No real change in our weather pattern of recent weeks for us today. Thornton will once again see temperatures well above normal along with just a slight chance for storms.

We start out the day with mostly sunny skies then will see a few more clouds intrude in the afternoon as moisture increases. Temperatures will once again be climbing to a high in the low 90s.

After 2:00pm a few, isolated thunderstorms will be possible from then into the evening. Gusty winds however look to be the biggest threat, perhaps a shower if conditions are just right.

Tonight skies will gradually clear and lows will be around 60 degrees. m

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A toasty Tuesday for Thornton with temps once again well above normal

Tuesday, September 12th, 2017 5:07am MST

A toasty Tuesday for Thornton with temps once again well above normal. Another 90+ degree day ahead for us with dry conditions and no break from the pattern we have been in for recent weeks. There is however some hope on the horizon for late in the week that we will see things cool down.

For today we will see mostly sunny skies above for most of the day with a few more clouds in the late afternoon and evening. Temperatures will be climbing steadily early and heading toward a mid-afternoon high in the low 90s. No thunderstorm activity is expected in our area.

Tonight, skies will be mostly clear and lows will be near the 60 degree mark.

Looking ahead, the mercury will remain above normal Wednesday and Thursday but then a low pressure system should bring some relief. Highs will be just a hair above normal Friday then dip into the 70s for this weekend. Get more details in the extended weather forecast here.

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Mourners sob, sift wreckage of huge Mexico quake

Monday, September 11th, 2017 10:03am MST

Sobbing Mexican families followed coffins through the streets and picked nervously at the ruins of their homes Sunday as help trickled in after a huge earthquake killed 90 people. “I don’t know if I am crying from sadness, from shock, or from fear of what might happen next, and how we will live,” said Refugio Portales,… » Click here to read the rest of Mourners sob, sift wreckage of huge Mexico quake

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Irma weakens but 6.2 million without power in Florida

Monday, September 11th, 2017 9:59am MST

Monster storm Irma, which ripped a deadly path through the Caribbean, started to weaken Monday though it was still whipping parts of Florida with fearsome winds and rain, leaving 6.2 million people without power. The death toll jumped to at least 40 as Cuba said 10 people had been killed there over the weekend as the… » Click here to read the rest of Irma weakens but 6.2 million without power in Florida

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