Average Weather in December in Chelan Washington, United States
In Chelan, the month of December is characterized by falling daily high temperatures, with daily highs decreasing by 5°F, from 35°F to 30°F over the course of the month, and rarely exceeding 44°F or dropping below 19°F. The lowest daily average high temperature is 30°F on December 24.
Daily low temperatures decrease by 4°F, from 25°F to 21°F, rarely falling below 9°F or exceeding 34°F. The lowest daily average low temperature is 21°F on December 30.
For reference, on August 2, the hottest day of the year, temperatures in Chelan typically range from 60°F to 88°F, while on December 30, the coldest day of the year, they range from 21°F to 30°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 Chelan experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 65% throughout the month.
The clearest day of the month is December 7, with clear, mostly clear, or partly cloudy conditions 36% of the time.
For reference, on January 15, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 67%, while on August 3, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 80%.
Cloud Cover Categories in December
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Chelan, the chance of a wet day over the course of December is decreasing, starting the month at 32% and ending it at 28%.
For reference, the year's highest daily chance of a wet day is 32% on December 1, and its lowest chance is 5% on August 17.
Over the course of December in Chelan, the chance of a day with only rain decreases from 13% to 5%, the chance of a day with mixed snow and rain decreases from 8% to 5%, and the chance of a day with only snow increases from 11% to 19%.
Probability of Precipitation in December
The average sliding 31-day rainfall during December in Chelan is decreasing, starting the month at 1.2 inches, when it rarely exceeds 2.6 inches or falls below 0.2 inches, and ending the month at 0.6 inches, when it rarely exceeds 1.4 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 Chelan is gradually increasing, starting the month at 0.9 inches, when it rarely exceeds 1.8 inches or falls below 0.1 inches, and ending the month at 1.2 inches, when it rarely exceeds 2.1 inches or falls below 0.3 inches.
The highest average 31-day liquid-equivalent accumulation is 1.2 inches on December 27.
Average Monthly Liquid-Equivalent Snowfall in December
Over the course of December in Chelan, the length of the day is essentially constant. The shortest day of the month is December 21, with 8 hours, 24 minutes of daylight and the longest day is December 1, with 8 hours, 41 minutes of daylight.
Hours of Daylight and Twilight in December
The earliest sunrise of the month in Chelan is 7:28 AM on December 1 and the latest sunrise is 21 minutes later at 7:49 AM on December 31.
The earliest sunset is 4:07 PM on December 10 and the latest sunset is 10 minutes later at 4:17 PM on December 31.
Daylight saving time is observed in Chelan during 2017, 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 5:01 AM and sets 16 hours, 1 minute later, at 9:02 PM, while on December 21, the shortest day of the year, it rises at 7:46 AM and sets 8 hours, 24 minutes later, at 4:10 PM.
Sunrise & Sunset with Twilight and Daylight Saving Time in December
The chance that a given day will be muggy in Chelan is essentially constant during December, remaining around 0% throughout.
For reference, on July 29, 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
The average hourly wind speed in Chelan is essentially constant during December, remaining within 0.1 miles per hour of 4.4 miles per hour throughout.
For reference, on May 7, the windiest day of the year, the daily average wind speed is 5.7 miles per hour, while on January 6, the calmest day of the year, the daily average wind speed is 4.2 miles per hour.
Average Wind Speed in December
Wind Direction in December
The growing season in Chelan typically lasts for 6.2 months (188 days), from around April 16 to around October 22, rarely starting before March 28 or after May 7, and rarely ending before October 6 or after November 7.
The month of December in Chelan 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 Chelan is essentially constant during December, remaining around 2,579°F throughout.
Growing Degree Days in December
The average daily incident shortwave solar energy in Chelan 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 24.
Average Daily Incident Shortwave Solar Energy in December
For the purposes of this report, the geographical coordinates of Chelan are 47.841 deg latitude, -120.016 deg longitude, and 1,640 ft elevation.
The topography within 2 miles of Chelan contains large variations in elevation, with a maximum elevation change of 2,310 feet and an average elevation above sea level of 1,553 feet. Within 10 miles contains large variations in elevation (4,416 feet). Within 50 miles also contains extreme variations in elevation (8,799 feet).
The area within 2 miles of Chelan is covered by grassland (45%) and shrubs (36%), within 10 miles by shrubs (42%) and grassland (23%), and within 50 miles by shrubs (47%) and trees (18%).
This report illustrates the typical weather in Chelan 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 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Chelan.
For each station, the records are corrected for the elevation difference between that station and Chelan 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 Chelan is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Chelan and a given station.
The stations contributing to this reconstruction are: Pangborn Field (43%, 51 kilometers, south); Ephrata Municipal Airport (27%, 70 kilometers, southeast); Omak Airport (23%, 79 kilometers, northeast); and Arlington Municipal Airport (7%, 164 kilometers, west).
Time zones for aiports and weather stations are provided by AskGeo.com .