Winter Weather in Thornton Colorado, United States
Daily high temperatures increase by 4°F, from 48°F to 52°F, rarely falling below 26°F or exceeding 66°F. The lowest daily average high temperature is 43°F on December 30.
Daily low temperatures increase by 2°F, from 26°F to 28°F, rarely falling below 5°F or exceeding 38°F. The lowest daily average low temperature is 22°F on December 30.
For reference, on July 13, the hottest day of the year, temperatures in Thornton typically range from 61°F to 88°F, while on December 30, the coldest day of the year, they range from 22°F to 43°F.
Average High and Low Temperature in the Winter in Thornton
The figure below shows you a compact characterization of the hourly average winter temperatures. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature in the Winter in Thornton
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The winter in Thornton experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 42% throughout the season.
The clearest day of the winter is January 13, with clear, mostly clear, or partly cloudy conditions 61% of the time.
For reference, on March 15, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 47%, while on September 13, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 75%.
Cloud Cover Categories in the Winter in Thornton
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Thornton, the chance of a wet day over the course of the winter is gradually increasing, starting the season at 8% and ending it at 10%.
For reference, the year's highest daily chance of a wet day is 30% on July 23, and its lowest chance is 6% on December 19.
Over the course of the winter in Thornton, the chance of a day with only rain increases from 2% to 4%, the chance of a day with mixed snow and rain remains an essentially constant 2% throughout, and the chance of a day with only snow remains an essentially constant 4% throughout.
Probability of Precipitation in the Winter in Thornton
To show variation within the season and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day rainfall during the winter in Thornton is essentially constant, remaining about 0.2 inches throughout, and rarely exceeding 1.0 inches or falling below -0.0 inches.
The lowest average 31-day accumulation is 0.1 inches on December 27.
Average Monthly Rainfall in the Winter in Thornton
We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. As with rainfall, we consider the liquid-equivalent snowfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day liquid-equivalent snowfall during the winter in Thornton is essentially constant, remaining about 0.2 inches throughout, and rarely exceeding 0.6 inches or falling to 0.0 inches.
The highest average 31-day liquid-equivalent accumulation is 0.3 inches on December 16. The lowest average 31-day liquid-equivalent accumulation is 0.2 inches on January 23.
Average Monthly Liquid-Equivalent Snowfall in the Winter in Thornton
Over the course of the winter in Thornton, the length of the day is rapidly increasing. From the start to the end of the season, the length of the day increases by 1 hour, 44 minutes, implying an average daily increase of 1 minute, 10 seconds, and weekly increase of 8 minutes, 8 seconds.
The shortest day of the winter is December 21, with 9 hours, 20 minutes of daylight and the longest day is February 28, with 11 hours, 16 minutes of daylight.
Hours of Daylight and Twilight in the Winter in Thornton
The latest sunrise of the winter in Thornton is 7:21 AM on January 4 and the earliest sunrise is 47 minutes earlier at 6:34 AM on February 28.
The earliest sunset is 4:34 PM on December 7 and the latest sunset is 1 hour, 16 minutes later at 5:50 PM on February 28.
Daylight saving time is observed in Thornton during 2021, but it neither starts nor ends during the winter, so the entire season is in standard time.
For reference, on June 21, the longest day of the year, the Sun rises at 5:31 AM and sets 15 hours, 0 minutes later, at 8:31 PM, while on December 21, the shortest day of the year, it rises at 7:17 AM and sets 9 hours, 20 minutes later, at 4:38 PM.
Sunrise & Sunset with Twilight and Daylight Saving Time in the Winter in Thornton
The figure below presents a compact representation of key lunar data for the winter of 2021. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.
Moon Rise, Set & Phases in the Winter in Thornton
We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.
The chance that a given day will be muggy in Thornton is essentially constant during the winter, remaining around 0% throughout.
For reference, on July 16, the muggiest day of the year, there are muggy conditions 0% of the time, while on January 1, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in the Winter in Thornton
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.
The average hourly wind speed in Thornton is gradually increasing during the winter, increasing from 8.6 miles per hour to 9.1 miles per hour over the course of the season.
For reference, on January 17, the windiest day of the year, the daily average wind speed is 9.8 miles per hour, while on August 19, the calmest day of the year, the daily average wind speed is 6.9 miles per hour.
The highest daily average wind speed during the winter is 9.8 miles per hour on January 19.
Average Wind Speed in the Winter in Thornton
The hourly average wind direction in Thornton throughout the winter is predominantly from the west, with a peak proportion of 66% on January 12.
Wind Direction in the Winter in Thornton
Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).
The growing season in Thornton typically lasts for 5.5 months (166 days), from around April 28 to around October 11, rarely starting before April 7 or after May 16, and rarely ending before September 19 or after November 2.
The winter in Thornton is reliably fully outside of the growing season.
Time Spent in Various Temperature Bands and the Growing Season in the Winter in Thornton
Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.
The average accumulated growing degree days in Thornton are very rapidly decreasing during the winter, decreasing by 3,125°F, from 3,166°F to 42°F, over the course of the season.
Growing Degree Days in the Winter in Thornton
This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.
The average daily incident shortwave solar energy in Thornton is rapidly increasing during the winter, rising by 1.7 kWh, from 2.6 kWh to 4.3 kWh, over the course of the season.
The lowest average daily incident shortwave solar energy during the winter is 2.4 kWh on December 22.
Average Daily Incident Shortwave Solar Energy in the Winter in Thornton
For the purposes of this report, the geographical coordinates of Thornton are 39.868 deg latitude, -104.972 deg longitude, and 5,351 ft elevation.
The topography within 2 miles of Thornton contains only modest variations in elevation, with a maximum elevation change of 446 feet and an average elevation above sea level of 5,273 feet. Within 10 miles contains only modest variations in elevation (830 feet). Within 50 miles contains very significant variations in elevation (9,806 feet).
The area within 2 miles of Thornton is covered by artificial surfaces (73%) and shrubs (27%), within 10 miles by shrubs (48%) and artificial surfaces (35%), and within 50 miles by grassland (32%) and trees (26%).
This report illustrates the typical weather in Thornton, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There are 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Thornton.
For each station, the records are corrected for the elevation difference between that station and Thornton according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at Thornton is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Thornton and a given station.
The stations contributing to this reconstruction are: Rocky Mountain Metropolitan Airport (KBJC, 39%, 13 kilometers, west); Denver / Stapleton International, Co. (KDNR, 35%, 16 kilometers, southeast); and Erie Municipal (KEIK, 27%, 18 kilometers, north).
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for airports and weather stations are provided by AskGeo.com .
Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.
The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.
We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.
We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.