Thornton, Colorado, USA
UpdatedWed, 16-Jan-2019 9:25pm MST 


ThorntonWeather.com on Twitter

ThorntonWeather.com on Facebook


Weather Geek Stuff - weathergeekstuff.com

Rocky Mountain Weather Network

Tony's Takes Photography


Recent News and Posts

Unseasonably warm temps, calm and dry conditions for Thornton’s weekend

Friday, July 6th, 2018 5:03am MST

Following last night’s nice little rain, we now dry out and warm up. Friday and the weekend will see temps above normal and dry conditions.

For Friday, mostly sunny skies will be above for most of the day with just a few more clouds in the late afternoon. Highs today will top out in the low 90s. Tonight, skies will be partly clear with lows in the low to mid-60s.

Saturday will offer up more sun than today and similarly dry, calm conditions. Highs will be in the mid-90s. Saturday night into Sunday morning lows will be down to the mid-60s under partly clear skies.

We close out the weekend on Sunday with a few more clouds but again with hot temps. Highs will be in the mid-90s under mostly sunny skies.

Have a great weekend!

Join the Discussion - Post your commentJoin the Discussion!

Cooler temperatures, good chances for storms for Thursday

Thursday, July 5th, 2018 5:03am MST

Moisture is on the increase and that will lead to more clouds today. Most notably though, it also gives us a decent chance to see some precipitation.

We start out under partly clear skies followed by the usual increase in cloud cover in the afternoon. Temperatures will be heading toward a high in the mid-80s offering a break from the 90s of the last few days.

This afternoon and brings a good chance for thunderstorms and showers. Some of these showers could become a bit heavy at times.

Tonight, any lingering showers should be done by midnight or so. Overnight lows will be down to around 60 degrees.

Join the Discussion - Post your commentJoin the Discussion!

June 2018 weather recap: Another warm, dry month

Wednesday, July 4th, 2018 7:20am MST

The running theme so far for 2018 seems to be warmer than normal temperatures and drier that average conditions.  That trend continued in June for Thornton.

Like May, June was somewhat a tale of two halves.  The first half of the month was marked by very dry conditions with no precipitation until the 16th of the month. Similarly, overall temperatures trended well above normal during the first half of June.

While the warm and dry conditions were notable, the most memorable weather event came on the evening of the 18th when large hail pounded the northern half of Thornton.  Extensive damage to homes and vehicles was seen as hailstones pushing 2 inches in diameter struck.

The month also featured Thornton’s hottest mercury reading in six years. We saw a high of 102.4 degrees on the 28th.  You have to go back to June 25, 2012 to find a warmer reading (102.9). Additionally, the reading ties for the second warmest high temperature ThorntonWeather.com has recorded since coming online in 2007.

Thornton saw an overall average temperature for the month of 71.3 degrees. This was well above the 30 year average June temperature for Denver of 67.4 degrees. Out at DIA where Denver’s official measurements are taken, it was even warmer with an average for the month of 72.4 degrees.

Temperatures ranged from a high of 102.4 degrees on the 28th down to a low of 46.8 degrees on the morning of the 25th.  The Mile High City saw it warmest reading of 105 on the 28th as well and its coldest reading of 44 degrees on the 2nd.

The National Weather Service reports that June 2018 will go into the books as the seventh warmest June on record for Denver.  Additionally, three days saw record tying or setting highs. The 5th brought a record high of 95 degrees, the 6th saw a record-tying high of 95 degrees and the 105 degree reading on the 28th was a record for that date.

Denver averages 1.98 inches of precipitation during the month of June. Both Thornton and Denver fell short of that mark.  Thornton saw 1.28 inches fall in its rain bucket while at the airport, it was even drier with only 0.43 inches.

Click here to view Thornton’s June 2018 climate report.

June 2018 temperature summary chart for Thornton, Colorado. (ThorntonWeather.com)

June 2018 temperature summary chart for Thornton, Colorado. (ThorntonWeather.com)

June 2018 precipitation summary chart for Thornton, Colorado. (ThorntonWeather.com)

June 2018 precipitation summary chart for Thornton, Colorado. (ThorntonWeather.com)

320 PM MDT SUN JUL 1 2018




                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
 HIGH             105   06/28/2018
 LOW               30   06/02/1951
HIGHEST           105R  06/28       104       1       99  06/20
LOWEST             44   06/02        30      14       42  06/13
AVG. MAXIMUM     88.8              82.4     6.4     85.5
AVG. MINIMUM     56.0              52.3     3.7     53.6
MEAN             72.4              67.4     5.0     69.5
DAYS MAX >= 90     16               7.9     8.1        9
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

 MAXIMUM         4.96   1882
 MINIMUM            T   1890
TOTALS           0.43              1.98   -1.55     0.33
DAILY AVG.       0.01              0.07   -0.06     0.01
DAYS >= .01         5               8.4    -3.4        5
DAYS >= .10         2               4.6    -2.6        2
DAYS >= .50         0               1.4    -1.4        0
DAYS >= 1.00        0               0.3    -0.3        0
 24 HR. TOTAL    0.25   06/17 TO 06/17

TOTAL             0.0               0.0
RECORD            0.4   1919

HEATING TOTAL       9                62     -53       25
 SINCE 7/1       5410              6058    -648     5109
COOLING TOTAL     241               133     108      167
 SINCE 1/1        289               155     134      173

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

AVERAGE WIND SPEED              10.5

AVERAGE SKY COVER               0.40
NUMBER OF DAYS FAIR               11
NUMBER OF DAYS PC                 16
NUMBER OF DAYS CLOUDY              3

AVERAGE RH (PERCENT)              42

THUNDERSTORMS            12   MIXED PRECIP           0
HEAVY RAIN                2   RAIN                   5
LIGHT RAIN                5   FREEZING RAIN          0
LT FREEZING RAIN          0   HAIL                   0
HEAVY SNOW                0   SNOW                   0
LIGHT SNOW                0   FOG W/VIS <=1/4 MILE   1
FOG                       5   HAZE                   2

Join the Discussion - Post your commentJoin the Discussion!

Thornton’s Independence Day to bring very warm temps, decent chance for storms

Wednesday, July 4th, 2018 5:46am MST

Not too bad of looking weather for a birthday celebration today. However, afternoon and evening thunderstorms are going to need close watch.

We start out under mostly sunny skies to be followed by a bit of an increase in cloud cover in the afternoon. Winds will be out of the northeast. High temperatures today will be a couple of degrees warmer than normal topping out at around the 90 degree mark.

The afternoon brings a chance for some isolated thunderstorm activity. Best opportunity comes between about 4:00pm and 8:00pm. Things then will begin to settle down and be wrapped up by midnight. Those thunderstorms this afternoon and evening could impact outdoor celebrations with gusty winds, some hail, brief, heavy rain. Be sure to keep an eye on the sky.

Overnight lows will be around 60 degrees.

Watch out for the storms with our interactive radar here.

Join the Discussion - Post your commentJoin the Discussion!

Toasty temps, just a slight chance for thunderstorms for Thornton’s Tuesday

Tuesday, July 3rd, 2018 5:01am MST

Another unseasonably warm day ahead for us. While there is a bit of a chance for storms, it is more likely we will be skipped over.

The day starts under sunny skies then this afternoon we will see an increase in cloud cover. By late afternoon, partly clear skies will be above. Some periods of haze from smoke will be seen.

After about 4:00pm and into the evening we see a slight chance for thunderstorms with gusty winds being the biggest threat from any that do develop. High temperatures today will top out in the mid-90s.

Tonight, skies will be partly clear with an overnight low in the low 60s.

Join the Discussion - Post your commentJoin the Discussion!

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

Monday, July 2nd, 2018 5:03am MST

A relatively pleasant day of weather start to your workweek. We’ll see a healthy dose of those blue, Colorado skies and temps will be above normal.

The day starts with sunny skies and those will last through this morning. This afternoon will bring a few clouds. Overall conditions will be calm with no thunderstorm activity expected in our area. Temperatures start out on the mild side which will aid their climb toward a high in the low to mid-90s.

Tonight, partly clear skies will be above with lows dipping to around the 60 degree mark.

Join the Discussion - Post your commentJoin the Discussion!

July 1 to July 7: This week in Denver weather history

Sunday, July 1st, 2018 6:04pm MST
This week in Denver weather history

July 1 to July 7: This week in Denver weather history

In our July weather preview we discussed how the month is not only Denver’s hottest but also its stormiest. Our look back at this week in Denver weather history helps to illustrate that fact. We start seeing 100+ degree days as well as many of the types of fast moving thunderstorm events expected this time of year.

From the National Weather Service:


In 1990…almost a year to date after the record breaking heat in early July 1989…the third longest heat wave in Denver history started. From June 29th through July 2nd the temperature reached 100 degrees or more on four consecutive days. The highest reading of 102 degrees occurred on the 29th…30th…and 1st. Combined with the 102 degree reading on June 27th this would have been the longest heat wave on record…but the temperature climbed to only 98 degrees on June 28th.


In 2000…the 29th marked the beginning of a near record hot streak for metro Denver. The high temperatures…as recorded at Denver International Airport…exceeded the 90 degree mark for 17 consecutive days from June 29th through July 15th. The record of 24 consecutive 90 degree or above days was set from July 13th through August 5th…2008.


In 1873…heavy rainfall overnight totaled 1.42 inches. Mountain peaks to the southwest of the city were covered with fresh snow on the morning of the 1st.


In 1915…northeast winds sustained to 41 mph with gusts to 50 mph occurred just before a thundershower in the evening. Rainfall was only 0.07 inch.

In 1941…unusually heavy thunderstorm rains flooded basements and blocked traffic. Water was curb high on many downtown streets. The thunderstorm also pelted the city with hail of unknown size. Rainfall in downtown Denver totaled 0.72 inch…but greater amounts likely occurred in other parts of the city.

In 1960…a severe dust devil moving through an Adams County suburban area blew over a fireworks stand…injuring an 11- year-old boy customer and two women operators of the stand. The boy was found under the demolished stand 100 feet away.

In 1961…hail as large as 1 1/4 inches in diameter was reported over east Denver.

In 1967…golf ball size hail fell over portions of metro Denver. Hail stones to 2 inches in diameter damaged roofs and broke windows in northeast Boulder. Marble to golf ball size hail fell at the Boulder airport. A funnel cloud was sighted over the foothills near Boulder. Hail stones of 1 to 2 inches in diameter were measured at Jefferson County Airport near Broomfield. Marble size hail fell in the vicinity of Arvada and Westminster.

In 1982…severe thunderstorms dropped large hail in Denver… Boulder…Commerce City…Lakewood…Wheat Ridge…Golden…and Arvada. Most locations reported hail size from 3/4 to 1 1/4 inches in diameter.

In 1990…the high temperature reached 102 degrees at Stapleton International Airport.

In 1998…hail to 1 1/2 inches in diameter fell near Bennett.

In 2001…the temperature climbed to a high of 101 degrees at Denver International Airport.

In 2016…a severe thunderstorm produced large hail in Castle Rock…ranging in size from 1 to 2 inches in diameter. The hail pummeled neighborhoods as it smashed cars and shattered windows. The storm caused extensive damage to shutters…roofs…siding and fencing.


In 1874…a streak of 18 consecutive days of 90 degrees tied for second with another streak that was later set in the summer of 1901. The record of 24 consecutive days was established in the summer of 2008.


In 2012…it was the hottest July on record in Denver since weather records began in 1872. The average temperature for the month was 78.9 degrees which was 4.7 degrees above normal. There were 27 days in which the high temperature equaled or exceeded 90 degrees…which established a new record. There were also 7 days in which the temperature equaled or exceeded 100 degrees which tied the record set in 2005.


In 1879…a severe hail storm produced considerable damage in the vicinity of Arvada. Some of the stones were unusually large…measuring 6.5 inches in circumference (2 inches in diameter) with an average weight of 1 ounce. The stones were uniformly large with one side concave. The greatest damage was to early wheat…cabbage…and vines. A tree just to the south of the weather station in downtown Denver was struck by lightning. Residents in the house 15 feet away were affected by the strike.

In 1885…thunderstorm winds were sustained to 50 mph in the city.

In 1892…an apparent cold front produced sustained northeast winds to 40 mph with gusts to 45 mph.

In 1955…a apparent microburst wind gust to 69 mph was recorded at Stapleton Airport where the brief strong wind reduced the visibility to zero in blowing dust.

In 1965…hail…up to 2 inches in diameter…struck southwest Adams and northeast Denver counties…damaging cars…windows… And foliage. Hail accumulated up to a foot deep. Wind gusts to 48 mph and hail to 1 inch in diameter fell at Stapleton International Airport where the large hail broke three storm windows and shredded shrubs at the U.S. Weather Bureau Upper Air building.

In 1968…a pilot reported a tornado 10 miles southeast of Parker.

In 1971…one inch diameter hail stones were reported in Adams County about 30 miles east of Denver.

In 1987…a large tornado touched down 10 miles northeast of Stapleton International Airport. The tornado was vertical and thick and kicked up a large dust and debris cloud. Later…it developed a sinuous rope-like shape as it slowly dissipated. The tornado was visible for 15 minutes. The twister occurred in open country and did only minor damage to a metal shed…porch…and mailbox. A man was killed by lightning in southwest Aurora. He was in his backyard and had a shovel in his hand at the time of the strike. A group of soccer players were hit by lightning on a field in Boulder. A 10-year-old boy was critically injured and hospitalized; fortunately he recovered. Six other people were knocked to the ground by the strike. Two of these were slightly injured. Golf ball size hail fell just east of Littleton and at Highlands Ranch. Hail as large as 3/4 inch in diameter was reported in Aurora and Parker and near Hudson and Franktown.

In 1988…a 45-year-old man was injured by lightning at Cheery Creek Reservoir. Administration of CPR probably saved his life.

In 1990…the temperature reached a high of 100 degrees at Stapleton International Airport.

In 1993…thunderstorm winds blew a roof off a barn near Parker…causing an estimated 15 hundred dollars damage.

In 1994…thunderstorm winds downed power lines in Boulder… Causing power outages. Winds gusted to 66 mph in Boulder… 64 mph in Arvada…and 60 mph in Golden.

In 1998…a small tornado touched down briefly near Barr Lake… But caused no damage.

In 2002…hail as large as 1 3/4 inches in diameter fell in the city of Denver and in Arapahoe County near Littleton. The low temperature of 69 degrees equaled the record high minimum for the date.

In 2006…lightning struck a teenager in Castle Rock as he was mowing his lawn and listening to an iPod. The teen suffered burns to his hands and feet…and had blood running from his ears when he was found. The victim’s eardrums were ruptured…which damaged his hearing. Lightning also struck a house in Castle Rock causing extensive damage to the roof and side of the home. Heavy rains caused flash flooding at Castlewood Canyon State Park near Franktown. The floodwaters destroyed four footbridges along the high trail. A culvert and several roads were washed out in the area. In addition… Two driveways crossing Cherry Creek were washed out near Prairie Canyon Ranch. Heavy rainfall also caused minor flooding on murphy and sand creeks…just east of Buckley AFB. Gun Club Road was closed between Alameda and Mississippi avenues…north of the Murphy Creek Golf Course…where 3 feet of standing water reportedly covered the road. A severe thunderstorm produced large hail to 7/8 inch in diameter in south Aurora near Cherry Creek.

In 2016…a weak landspout touched down briefly in and open field near Bennett.

» Click here to read the rest of July 1 to July 7: This week in Denver weather history

Join the Discussion - Post your commentJoin the Discussion!

Thornton’s July weather preview: Temperatures typically climb, PM storms the norm

Saturday, June 30th, 2018 4:45pm MST

Change is of course the one constant in Denver’s weather but come July, things actually get pretty consistent.

The standard formula for a day in July is a sunny morning, clouds developing in the late morning and early afternoon. Come mid-afternoon, thunderstorms are rolling off of the foothills and into the metro area and the eastern plains. These storms do occasionally reach severe status containing hail, gusty winds and heavy downpours of rain.

Check out our July weather preview for a complete look at what is in store for the month ahead.

Join the Discussion - Post your commentJoin the Discussion!

June 2018 top shots: Monthly photo slideshow

Saturday, June 30th, 2018 7:18am MST
June 4, 2018 - Sunset colors the virga late in the evening. (David Canfield)

June 4, 2018 – Sunset colors the virga late in the evening. (David Canfield)

The month of June typically sees springtime severe weather reach its height of activity in northeastern Colorado.

This affords the opportunity to capture extraordinary images of amazing weather phenomena from monstrous supercell thunderstorms to heavy rain, hail and even tornadoes.

  • Slideshow updated June 30, 2018

Showcasing images captured by ThorntonWeather.com readers as well as some of our own, our monthly slideshow covers the entire gamut of weather and nature related imagery.

Sunsets, sunrises, wildlife and of course every type of weather condition are vividly depicted.  June brings some very dynamic weather and the photos are a great way to see the stunning variety.

To learn more about how to send your photo to us for inclusion in the slideshow, see below the slideshow.

What is missing in the slideshow above?  Your photo!

Our monthly photo slideshow is going to feature images that we have taken but more importantly images that you have captured.  The photos can be of anything even remotely weather-related.

Landscapes, current conditions, wildlife, pets, kids.  Whimsical, newsy, artsy.  Taken at the zoo, some other area attraction, a local park, a national park or your backyard.  You name it, we want to see and share it!

Images can be taken in Thornton, Denver or anywhere across the extraordinary Centennial State.  We’ll even take some from out of state if we can tie it to Colorado somehow.

We’ll keep the criteria very open to interpretation with just about any image eligible to be shown in our slideshows.

What do you win for having your image in our slideshow?  We are just a ‘mom and pop’ outfit and make no money from our site so we really don’t have the means to provide prizes.  However you will have our undying gratitude and the satisfaction that your images are shared on the most popular website in Thornton.

To share you images with us and get them included in the slideshow just email them to us or share them with ThorntonWeather.com on any of the various social media outlets.  Links are provided below.

So come on, get those camera’s rolling!

Join the Discussion - Post your commentJoin the Discussion!

Lightning and wildfires – Hand in hand hazards

Saturday, June 30th, 2018 6:00am MST

Wildfires and lightning go hand in hand as half of Colorado’s blazes are ignited by lightning.

Wildfires are not strictly a weather-related threat.  The weather does however play a significant role in starting fires and in the ability of firefighters to battle them.

From the National Weather Service:

500 PM MDT SAT JUNE 30 2018

Colorado Lightning Safety Week concludes today…with wildfires being the final topic.

During the past week we have presented lightning information and safety rules.  Although wildfires are not an actual weather phenomenon…wildfires are directly related to lightning and other weather elements.

Normally…the wildfire threat in Colorado increases significantly after the middle of June and usually peaks in early July…and remains high through august and early September.  Colorado averages about 2500 wildfires each year.

About half of all forest fires in Colorado are ignited by lightning. Additionally…many rangeland and wheat field fires are caused by lightning. Many of these lightning caused wildfires occur in the absence of rain and are the result of what is referred to as dry thunderstorms.

Lightning is often accompanied by strong winds from thunderstorms. These winds can quickly turn smoldering organic material into a raging fire.  Thunderstorm winds tend to be erratic in direction and speed…posing one of the greatest dangers for firefighters.

Lightning that strikes the ground is usually divided into two categories…negative and positive strikes… Depending on the ionic source region of the thunderstorm.  The negative strikes are far more common than positive strikes.  The positive strikes are more intense and have a longer duration than the negative strikes and are more likely to ignite a fire.  Lightning detection technology provides land managers and weather forecasters with the ability to identify the general location and charge category of each lightning strike.

National Weather Service forecasters help land managers and firefighters by producing fire weather zone forecasts on a daily basis.  Spot fire weather forecasts are also provided for those who work on prescribed burns or specific wildfires.  Forecasters also issue red flag warnings for use by land managers when the combination of dry vegetation and critical weather conditions will result in a high potential for the development and spread of

Wildfires.  Land managers…in turn… Typically inform the general public of the fire danger in national parks…forests… And other public lands.

During periods of extreme fire danger in forests and rangelands…

  • You should avoid being in areas where you might become trapped by a wildfire.
  • You should avoid the use of matches or anything else which could ignite a fire.
  • Make sure that hot parts of motorized equipment…such as mufflers…are not allowed to come in contact with dry grasses or other potentially flammable material.
  • If you become trapped or cut off by a wildfire seek shelter in areas with little or no fuel…such as rock slide areas or lakes.

For more information on wildfires and fire safety…please check out the following web addresses…

Lightning Safety and Wildfire Awareness Series:

Join the Discussion - Post your commentJoin the Discussion!