Average Weather in December in Lake Arrowhead California, United States
Daily high temperatures decrease by 4°F, from 53°F to 50°F, rarely falling below 40°F or exceeding 62°F. The lowest daily average high temperature is 49°F on December 24.
Daily low temperatures decrease by 2°F, from 30°F to 28°F, rarely falling below 20°F or exceeding 38°F. The lowest daily average low temperature is 28°F on December 25.
For reference, on July 27, the hottest day of the year, temperatures in Lake Arrowhead typically range from 57°F to 85°F, while on December 25, the coldest day of the year, they range from 28°F to 49°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 Lake Arrowhead experiences gradually increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 37% to 41%. The highest chance of overcast or mostly cloudy conditions is 41% on December 28.
The clearest day of the month is December 1, with clear, mostly clear, or partly cloudy conditions 63% of the time.
For reference, on February 21, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 46%, while on September 7, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 90%.
Cloud Cover Categories in December
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Lake Arrowhead, the chance of a wet day over the course of December is increasing, starting the month at 10% and ending it at 14%.
For reference, the year's highest daily chance of a wet day is 18% on February 21, and its lowest chance is 1% on June 15.
Over the course of December in Lake Arrowhead, the chance of a day with only rain remains an essentially constant 9% throughout, the chance of a day with mixed snow and rain increases from 1% to 4%, 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 Lake Arrowhead is gradually increasing, starting the month at 0.8 inches, when it rarely exceeds 1.9 inches, and ending the month at 1.3 inches, when it rarely exceeds 3.8 inches or falls below 0.1 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 Lake Arrowhead is essentially constant, remaining about 0.2 inches throughout, and rarely exceeding 0.9 inches or falling below -0.0 inches.
Average Monthly Liquid-Equivalent Snowfall in December
Over the course of December in Lake Arrowhead, the length of the day is essentially constant. The shortest day of the month is December 21, with 9 hours, 52 minutes of daylight and the longest day is December 1, with 10 hours, 2 minutes of daylight.
Hours of Daylight and Twilight in December
The earliest sunrise of the month in Lake Arrowhead is 6:36 AM on December 1 and the latest sunrise is 18 minutes later at 6:54 AM on December 31.
The earliest sunset is 4:38 PM on December 5 and the latest sunset is 11 minutes later at 4:49 PM on December 31.
Daylight saving time is observed in Lake Arrowhead 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 5:37 AM and sets 14 hours, 27 minutes later, at 8:03 PM, while on December 21, the shortest day of the year, it rises at 6:50 AM and sets 9 hours, 52 minutes later, at 4:42 PM.
Sunrise & Sunset with Twilight and Daylight Saving Time in December
The chance that a given day will be muggy in Lake Arrowhead is essentially constant during December, remaining around 0% throughout.
For reference, on August 22, the muggiest day of the year, there are muggy conditions 0% of the time, while on September 22, 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 Lake Arrowhead is essentially constant during December, remaining within 0.2 miles per hour of 7.2 miles per hour throughout.
For reference, on April 26, the windiest day of the year, the daily average wind speed is 7.9 miles per hour, while on September 9, the calmest day of the year, the daily average wind speed is 5.8 miles per hour.
The highest daily average wind speed during December is 7.4 miles per hour on December 10.
Average Wind Speed in December
Wind Direction in December
Lake Arrowhead 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 Lake Arrowhead is gradually decreasing during December, falling by 2°F, from 62°F to 59°F, over the course of the month.
Average Water Temperature in December
The growing season in Lake Arrowhead typically lasts for 6.5 months (199 days), from around April 18 to around November 3, rarely starting before March 22 or after May 11, and rarely ending before October 17 or after November 20.
The month of December in Lake Arrowhead 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 Lake Arrowhead are essentially constant during December, remaining within 9°F of 2,992°F throughout.
Growing Degree Days in December
The average daily incident shortwave solar energy in Lake Arrowhead is essentially constant during December, remaining within 0.2 kWh of 3.2 kWh throughout.
The lowest average daily incident shortwave solar energy during December is 3.0 kWh on December 22.
Average Daily Incident Shortwave Solar Energy in December
For the purposes of this report, the geographical coordinates of Lake Arrowhead are 34.248 deg latitude, -117.189 deg longitude, and 5,207 ft elevation.
The topography within 2 miles of Lake Arrowhead contains very significant variations in elevation, with a maximum elevation change of 1,896 feet and an average elevation above sea level of 5,314 feet. Within 10 miles contains very significant variations in elevation (7,244 feet). Within 50 miles also contains extreme variations in elevation (11,394 feet).
The area within 2 miles of Lake Arrowhead is covered by trees (66%) and shrubs (33%), within 10 miles by shrubs (68%) and trees (19%), and within 50 miles by shrubs (77%).
This report illustrates the typical weather in Lake Arrowhead 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 Lake Arrowhead.
For each station, the records are corrected for the elevation difference between that station and Lake Arrowhead 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 Lake Arrowhead is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Lake Arrowhead and a given station.
The stations contributing to this reconstruction are: San Bernardino International Airport (27%, 18 kilometers, south); Southern California Logistics Airport (50%, 41 kilometers, northwest); and Twenty-Nine Palms, Marine Corps Air-Ground Combat Center (24%, 94 kilometers, east).
Time zones for aiports and weather stations are provided by AskGeo.com .