Average Weather in December in Pullman Washington, United States
Daily high temperatures decrease by 4°F, from 39°F to 35°F, rarely falling below 24°F or exceeding 49°F. The lowest daily average high temperature is 35°F on December 23.
Daily low temperatures decrease by 3°F, from 29°F to 25°F, rarely falling below 11°F or exceeding 38°F. The lowest daily average low temperature is 25°F on December 23.
For reference, on August 3, the hottest day of the year, temperatures in Pullman typically range from 52°F to 86°F, while on December 23, the coldest day of the year, they range from 25°F to 35°F.
Average High and Low Temperature in December
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on December. 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 December
The month of December in Pullman experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 67% throughout the month.
The clearest day of the month is December 14, with clear, mostly clear, or partly cloudy conditions 34% of the time.
For reference, on January 15, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 69%, while on July 29, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 81%.
Cloud Cover Categories in December
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 Pullman, the chance of a wet day over the course of December is rapidly decreasing, starting the month at 38% and ending it at 31%.
For reference, the year's highest daily chance of a wet day is 38% on November 28, and its lowest chance is 7% on August 5.
Over the course of December in Pullman, the chance of a day with only rain decreases from 28% to 16%, the chance of a day with mixed snow and rain increases from 5% to 9%, and the chance of a day with only snow increases from 4% to 7%.
Probability of Precipitation in December
The average sliding 31-day rainfall during December in Pullman is decreasing, starting the month at 2.1 inches, when it rarely exceeds 3.6 inches or falls below 0.8 inches, and ending the month at 1.6 inches, when it rarely exceeds 2.9 inches or falls below 0.4 inches.
Average Monthly Rainfall in December
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 December in Pullman is gradually increasing, starting the month at 0.3 inches, when it rarely exceeds 0.8 inches, and ending the month at 0.6 inches, when it rarely exceeds 1.5 inches.
The highest average 31-day liquid-equivalent accumulation is 0.6 inches on December 31.
Average Monthly Liquid-Equivalent Snowfall in December
Over the course of December in Pullman, the length of the day is essentially constant. The shortest day of the month is December 21, with 8 hours, 33 minutes of daylight and the longest day is December 1, with 8 hours, 50 minutes of daylight.
Hours of Daylight and Twilight in December
The earliest sunrise of the month in Pullman is 7:12 AM on December 1 and the latest sunrise is 21 minutes later at 7:33 AM on December 31.
The earliest sunset is 4:00 PM on December 10 and the latest sunset is 10 minutes later at 4:10 PM on December 31.
Daylight saving time is observed in Pullman during 2018, but it neither starts nor ends during December, so the entire month is in standard time.
For reference, on June 21, the longest day of the year, the Sun rises at 4:54 AM and sets 15 hours, 52 minutes later, at 8:46 PM, while on December 21, the shortest day of the year, it rises at 7:30 AM and sets 8 hours, 33 minutes later, at 4:03 PM.
Sunrise & Sunset with Twilight and Daylight Saving Time in December
The chance that a given day will be muggy in Pullman is essentially constant during December, remaining around 0% throughout.
For reference, on July 6, the muggiest day of the year, there are muggy conditions 0% of the time, while on October 4, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in December
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The average hourly wind speed in Pullman is essentially constant during December, remaining within 0.2 miles per hour of 7.3 miles per hour throughout.
For reference, on March 27, the windiest day of the year, the daily average wind speed is 7.6 miles per hour, while on August 11, the calmest day of the year, the daily average wind speed is 6.0 miles per hour.
Average Wind Speed in December
Wind Direction in December
The growing season in Pullman typically lasts for 5.1 months (156 days), from around May 1 to around October 4, rarely starting before April 7 or after May 19, and rarely ending before September 14 or after October 27.
The month of December in Pullman is reliably fully outside of the growing season.
Time Spent in Various Temperature Bands and the Growing Season in December
The average accumulated growing degree days in Pullman are essentially constant during December, remaining around 2,086°F throughout.
Growing Degree Days in December
The average daily incident shortwave solar energy in Pullman is essentially constant during December, remaining within 0.1 kWh of 1.2 kWh throughout.
The lowest average daily incident shortwave solar energy during December is 1.1 kWh on December 23.
Average Daily Incident Shortwave Solar Energy in December
For the purposes of this report, the geographical coordinates of Pullman are 46.731 deg latitude, -117.180 deg longitude, and 2,543 ft elevation.
The topography within 2 miles of Pullman contains only modest variations in elevation, with a maximum elevation change of 390 feet and an average elevation above sea level of 2,517 feet. Within 10 miles contains only modest variations in elevation (2,182 feet). Within 50 miles contains large variations in elevation (5,833 feet).
The area within 2 miles of Pullman is covered by cropland (73%) and artificial surfaces (21%), within 10 miles by cropland (96%), and within 50 miles by cropland (40%) and shrubs (26%).
This report illustrates the typical weather in Pullman year round, 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 5 weather stations near enough to contribute to our estimation of the temperature and dew point in Pullman.
For each station, the records are corrected for the elevation difference between that station and Pullman 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 Pullman is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Pullman and a given station.
The stations contributing to this reconstruction are: Pullman–Moscow Regional Airport (94%, 5.6 kilometers, east); Lewiston–Nez Perce County Airport (3.2%, 42 kilometers, south); Spokane International Airport (1.2%, 103 kilometers, north); Walla Walla Regional Airport (1.0%, 111 kilometers, southwest); and Grant County International Airport (0.5%, 171 kilometers, west).
Time zones for aiports and weather stations are provided by AskGeo.com .