Average Weather in December in Bellevue Washington, United States
Daily high temperatures decrease by 2°F, from 48°F to 46°F, rarely falling below 37°F or exceeding 54°F. The lowest daily average high temperature is 46°F on December 23.
Daily low temperatures decrease by 2°F, from 39°F to 37°F, rarely falling below 27°F or exceeding 47°F.
For reference, on August 3, the hottest day of the year, temperatures in Bellevue typically range from 59°F to 79°F, while on January 1, the coldest day of the year, they range from 37°F to 46°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 Bellevue experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 73% throughout the month.
The clearest day of the month is December 21, with clear, mostly clear, or partly cloudy conditions 28% of the time.
For reference, on January 19, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 74%, while on August 3, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 74%.
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 Bellevue, the chance of a wet day over the course of December is rapidly decreasing, starting the month at 58% and ending it at 51%.
For reference, the year's highest daily chance of a wet day is 59% on November 18, and its lowest chance is 9% on August 5.
Over the course of December in Bellevue, the chance of a day with only rain decreases from 56% to 47%, 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 1% throughout.
Probability of Precipitation in December
The average sliding 31-day rainfall during December in Bellevue is rapidly decreasing, starting the month at 8.0 inches, when it rarely exceeds 12.5 inches or falls below 3.7 inches, and ending the month at 6.7 inches, when it rarely exceeds 10.4 inches or falls below 3.5 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 Bellevue is essentially constant, remaining about 0.1 inches throughout, and rarely exceeding 0.8 inches or falling below -0.0 inches.
The highest average 31-day liquid-equivalent accumulation is 0.2 inches on December 30.
Average Monthly Liquid-Equivalent Snowfall in December
Over the course of December in Bellevue, the length of the day is essentially constant. The shortest day of the month is December 21, with 8 hours, 26 minutes of daylight and the longest day is December 1, with 8 hours, 43 minutes of daylight.
Hours of Daylight and Twilight in December
The earliest sunrise of the month in Bellevue is 7:36 AM on December 1 and the latest sunrise is 21 minutes later at 7:57 AM on December 31.
The earliest sunset is 4:17 PM on December 11 and the latest sunset is 10 minutes later at 4:26 PM on December 31.
Daylight saving time is observed in Bellevue 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 5:10 AM and sets 15 hours, 59 minutes later, at 9:10 PM, while on December 21, the shortest day of the year, it rises at 7:54 AM and sets 8 hours, 26 minutes later, at 4:19 PM.
Sunrise & Sunset with Twilight and Daylight Saving Time in December
The chance that a given day will be muggy in Bellevue is essentially constant during December, remaining around 0% throughout.
For reference, on August 6, 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 December
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The average hourly wind speed in Bellevue is essentially constant during December, remaining within 0.1 miles per hour of 5.2 miles per hour throughout.
For reference, on December 4, the windiest day of the year, the daily average wind speed is 5.3 miles per hour, while on August 2, the calmest day of the year, the daily average wind speed is 2.7 miles per hour.
The highest daily average wind speed during December is 5.3 miles per hour on December 4.
Average Wind Speed in December
Wind Direction in December
Bellevue is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.
The average surface water temperature in Bellevue is gradually decreasing during December, falling by 2°F, from 49°F to 47°F, over the course of the month.
Average Water Temperature in December
The growing season in Bellevue typically lasts for 8.6 months (265 days), from around March 1 to around November 21, rarely starting before February 9 or after March 21, and rarely ending before October 30 or after December 18.
The month of December in Bellevue is more likely than not fully outside of the growing season, with the chance that a given day is in the growing season rapidly decreasing from 32% to 2% over the course of the month.
Time Spent in Various Temperature Bands and the Growing Season in December
The average accumulated growing degree days in Bellevue are essentially constant during December, remaining within 3°F of 2,282°F throughout.
Growing Degree Days in December
The average daily incident shortwave solar energy in Bellevue is essentially constant during December, remaining around 0.9 kWh throughout.
The lowest average daily incident shortwave solar energy during December is 0.9 kWh on December 25.
Average Daily Incident Shortwave Solar Energy in December
For the purposes of this report, the geographical coordinates of Bellevue are 47.610 deg latitude, -122.201 deg longitude, and 125 ft elevation.
The topography within 2 miles of Bellevue contains only modest variations in elevation, with a maximum elevation change of 367 feet and an average elevation above sea level of 121 feet. Within 10 miles contains only modest variations in elevation (1,955 feet). Within 50 miles contains very significant variations in elevation (7,910 feet).
The area within 2 miles of Bellevue is covered by artificial surfaces (67%), water (16%), and herbaceous vegetation (10%), within 10 miles by artificial surfaces (58%) and trees (16%), and within 50 miles by trees (53%) and artificial surfaces (13%).
This report illustrates the typical weather in Bellevue 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 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Bellevue.
For each station, the records are corrected for the elevation difference between that station and Bellevue 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 Bellevue is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Bellevue and a given station.
The stations contributing to this reconstruction are: King County International Airport (49%, 12 kilometers, southwest); Renton Municipal Airport (42%, 13 kilometers, south); and Snohomish County Airport (Paine Field) (9%, 34 kilometers, north).
Time zones for aiports and weather stations are provided by AskGeo.com .