Fall Weather in Denver Colorado, United States
Daily high temperatures decrease by 34°F, from 84°F to 49°F, rarely falling below 33°F or exceeding 92°F.
Daily low temperatures decrease by 31°F, from 57°F to 27°F, rarely falling below 14°F or exceeding 64°F.
For reference, on July 10, the hottest day of the year, temperatures in Denver typically range from 62°F to 89°F, while on December 30, the coldest day of the year, they range from 22°F to 44°F.
The figure below shows you a compact characterization of the hourly average fall 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.
Kırıkkale, Turkey (6,354 miles away) is the far-away foreign place with temperatures most similar to Denver (view comparison).
The fall in Denver experiences increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 30% to 41%. The lowest chance of overcast or mostly cloudy conditions is 25% on September 16.
The clearest day of the fall is September 16, with clear, mostly clear, or partly cloudy conditions 75% 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%.
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Denver, the chance of a wet day over the course of the fall is very rapidly decreasing, starting the season at 21% and ending it at 8%.
For reference, the year's highest daily chance of a wet day is 31% on July 22, and its lowest chance is 6% on December 19.
Over the course of the fall in Denver, the chance of a day with only rain decreases from 21% to 2%, the chance of a day with mixed snow and rain increases from 0% to 2%, and the chance of a day with only snow increases from 0% to 4%.
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 fall in Denver is decreasing, starting the season at 1.1 inches, when it rarely exceeds 2.0 inches or falls below 0.3 inches, and ending the season at 0.2 inches, when it rarely exceeds 0.4 inches.
As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day snowfall during the fall in Denver is increasing, starting the season at 0.0 inches, when it rarely exceeds 0.1 inches, and ending the season at 2.3 inches, when it rarely exceeds 5.0 inches or falls below 0.3 inches.
Over the course of the fall in Denver, the length of the day is very rapidly decreasing. From the start to the end of the season, the length of the day decreases by 3 hours, 28 minutes, implying an average daily decrease of 2 minutes, 19 seconds, and weekly decrease of 16 minutes, 10 seconds.
The shortest day of the fall is November 30, with 9 hours, 36 minutes of daylight and the longest day is September 1, with 13 hours, 3 minutes of daylight.
The earliest sunrise of the fall in Denver is 6:27 AM on September 1 and the latest sunrise is 1 hour, 4 minutes later at 7:31 AM on November 4.
The latest sunset is 7:31 PM on September 1 and the earliest sunset is 2 hours, 55 minutes earlier at 4:36 PM on November 30.
Daylight saving time (DST) ends at 1:00 AM on November 5, 2023, shifting sunrise and sunset to be an hour earlier.
For reference, on June 21, the longest day of the year, the Sun rises at 5:32 AM and sets 14 hours, 59 minutes later, at 8:31 PM, while on December 22, the shortest day of the year, it rises at 7:17 AM and sets 9 hours, 21 minutes later, at 4:39 PM.
The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.
The figure below presents a compact representation of key lunar data for the fall of 2023. 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.
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 Denver is essentially constant during the fall, remaining around 0% throughout.
For reference, on July 15, 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.
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 Denver is increasing during the fall, increasing from 7.0 miles per hour to 8.6 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 9.7 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 hourly average wind direction in Denver throughout the fall is predominantly from the west, with a peak proportion of 59% on November 30.
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 Denver typically lasts for 5.5 months (169 days), from around April 27 to around October 13, rarely starting before April 6 or after May 15, and rarely ending before September 23 or after November 2.
During the fall in Denver, the chance that a given day is within the growing season is very rapidly decreasing falling from 100% to 0% over the course of the season.
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 Denver are rapidly increasing during the fall, increasing by 706°F, from 2,612°F to 3,317°F, over the course of the season.
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 Denver is very rapidly decreasing during the fall, falling by 3.4 kWh, from 6.1 kWh to 2.7 kWh, over the course of the season.
For the purposes of this report, the geographical coordinates of Denver are 39.739 deg latitude, -104.985 deg longitude, and 5,272 ft elevation.
The topography within 2 miles of Denver contains only modest variations in elevation, with a maximum elevation change of 243 feet and an average elevation above sea level of 5,248 feet. Within 10 miles contains only modest variations in elevation (1,562 feet). Within 50 miles contains very significant variations in elevation (9,649 feet).
The area within 2 miles of Denver is covered by shrubs (60%) and artificial surfaces (38%), within 10 miles by artificial surfaces (61%) and shrubs (32%), and within 50 miles by grassland (33%) and trees (28%).
This report illustrates the typical weather in Denver, 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 Denver.
For each station, the records are corrected for the elevation difference between that station and Denver 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 Denver is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Denver and a given station.
The stations contributing to this reconstruction are:
To get a sense of how much these sources agree with each other, you can view a comparison of Denver and the stations that contribute to our estimates of its temperature history and climate. Please note that each source's contribution is adjusted for elevation and the relative change present in the MERRA-2 data.
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 © OpenStreetMap contributors.
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.
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