Average Weather in December in Jackson California, United States
Daily high temperatures decrease by 3°F, from 56°F to 53°F, rarely falling below 45°F or exceeding 64°F. The lowest daily average high temperature is 53°F on December 27.
Daily low temperatures decrease by 2°F, from 42°F to 40°F, rarely falling below 32°F or exceeding 49°F. The lowest daily average low temperature is 40°F on December 30.
For reference, on July 19, the hottest day of the year, temperatures in Jackson typically range from 65°F to 91°F, while on December 30, the coldest day of the year, they range from 40°F to 53°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 Jackson experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 54% throughout the month.
The clearest day of the month is December 1, with clear, mostly clear, or partly cloudy conditions 48% of the time.
For reference, on February 21, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 57%, while on July 29, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 91%.
Cloud Cover Categories in December
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Jackson, the chance of a wet day over the course of December is essentially constant, remaining around 28% throughout.
For reference, the year's highest daily chance of a wet day is 32% on February 20, and its lowest chance is 1% on August 1.
Probability of Precipitation in December
To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day rainfall during December in Jackson is increasing, starting the month at 3.8 inches, when it rarely exceeds 7.6 inches or falls below 0.7 inches, and ending the month at 4.5 inches, when it rarely exceeds 9.4 inches or falls below 0.4 inches.
Average Monthly Rainfall in December
Over the course of December in Jackson, the length of the day is essentially constant. The shortest day of the month is December 21, with 9 hours, 30 minutes of daylight and the longest day is December 1, with 9 hours, 42 minutes of daylight.
Hours of Daylight and Twilight in December
The earliest sunrise of the month in Jackson is 7:01 AM on December 1 and the latest sunrise is 19 minutes later at 7:19 AM on December 31.
The earliest sunset is 4:42 PM on December 7 and the latest sunset is 10 minutes later at 4:52 PM on December 31.
Daylight saving time is observed in Jackson 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 5:39 AM and sets 14 hours, 50 minutes later, at 8:30 PM, while on December 21, the shortest day of the year, it rises at 7:16 AM and sets 9 hours, 30 minutes later, at 4:46 PM.
Sunrise & Sunset with Twilight and Daylight Saving Time in December
The chance that a given day will be muggy in Jackson is essentially constant during December, remaining around 0% throughout.
For reference, on September 10, 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 Jackson is essentially constant during December, remaining within 0.1 miles per hour of 6.1 miles per hour throughout.
For reference, on December 14, the windiest day of the year, the daily average wind speed is 6.2 miles per hour, while on September 24, the calmest day of the year, the daily average wind speed is 5.0 miles per hour.
The highest daily average wind speed during December is 6.2 miles per hour on December 14.
Average Wind Speed in December
Wind Direction in December
The growing season in Jackson typically lasts for 10 months (310 days), from around February 5 to around December 12, rarely starting after April 2, or ending before November 17.
During December in Jackson, the chance that a given day is within the growing season is rapidly decreasing falling from 70% to 31% 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 Jackson are essentially constant during December, remaining within 16°F of 4,264°F throughout.
Growing Degree Days in December
The average daily incident shortwave solar energy in Jackson is essentially constant during December, remaining within 0.1 kWh of 2.3 kWh throughout.
The lowest average daily incident shortwave solar energy during December is 2.2 kWh on December 23.
Average Daily Incident Shortwave Solar Energy in December
For the purposes of this report, the geographical coordinates of Jackson are 38.349 deg latitude, -120.774 deg longitude, and 1,375 ft elevation.
The topography within 2 miles of Jackson contains significant variations in elevation, with a maximum elevation change of 758 feet and an average elevation above sea level of 1,372 feet. Within 10 miles contains significant variations in elevation (2,808 feet). Within 50 miles contains large variations in elevation (10,322 feet).
The area within 2 miles of Jackson is covered by grassland (81%) and shrubs (18%), within 10 miles by grassland (54%) and shrubs (26%), and within 50 miles by trees (28%) and grassland (25%).
This report illustrates the typical weather in Jackson 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 Jackson.
For each station, the records are corrected for the elevation difference between that station and Jackson 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 Jackson is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Jackson and a given station.
The stations contributing to this reconstruction are: Placerville Airport (39%, 41 kilometers, north); Sacramento Mather Airport (31%, 52 kilometers, northwest); Stockton Metropolitan Airport (24%, 65 kilometers, southwest); and Bridgeport Sonora Junction (6%, 110 kilometers, east).
Time zones for aiports and weather stations are provided by AskGeo.com .