San Diego Weather in December
Even though December brings the year's coldest weather to San Diego, California, the temperature still manages to make it well over 60 degrees Fahrenheit (16 degrees Celsius) on most days this month and rarely drops below 40 °F (4 °C) at night. This is also San Diego's least windy month.
This page gives detailed information on the typical December temperature, precipitation, sun, humidity, wind and storms for San Diego. The numbers here are historical averages based on climate data gathered at the San Diego International Airport, located on San Diego Bay near the city center.
|66 °F||December average high||19 °C|
|50 °F||December average low||10 °C|
December is the coldest month overall for San Diego and the 19th to 24th are its chilliest days. They have daily highs averaging 66 degrees Fahrenheit (19 degrees Celsius) and the minimum averages 49 °F (9 °C).
|28 days||60 °F max. or more (16 °C)|
|19 days||50 °F min. or less (10 °C)|
Usually every December day warms to over 50 °F (10 °C) in San Diego. The city averages 7 days this month when the thermometer reaches into the 70s °F (over 21 °C). Temperatures above 80 °F (26 °C) occur in December occur in some years.
At night, the thermometer dips as low as 40 °F (4 °C) only rarely in December, and not every year. December does not normally get cold enough for frost.
|1.7 in||total precipitation||42 mm|
|6 days||of rain|
Half the time, San Diego receives 0.6 to 2.5 inches (16 to 63 mm) of rainfall in December. One in four years has drier weather, while another one in four is wetter.
|14 days||clear skies|
The sun's rays reach the ground in San Diego during 73 percent of daylight hours on average in December, for a total of 227 hours in the month. Typically on 14 days this month the sky is mainly clear, with at most 30 percent cloud cover.
Sunlight in December at San Diego averages 10 hours and 2 minutes a day. The shortest days of the year, from around December 17th to 25th, last 10 hours and 0 minutes from sunrise to sunset.
|64 %||December average humidity|
The relative humidity in San Diego during December usually peaks at 71 percent just after midnight then drops to 50 percent by early afternoon.
|Local Time||1 am||4 am||7 am||10 am||1 pm||4 pm||7 pm||10 pm|
|5.6 mph||December wind speed average||9.0 kph|
The wind at San Diego is normally calmest during December.
|1 day||rainfall of 0.5 inches (13 mm) or more|
|0 days||with thunderstorms in December|
San Diego has a thunderstorm during December about once every three or four years.
The weather data here are long-term averages provided by the US National Centers for Environmental Information (NCEI). Temperature and precipitation are 1991-2020 normals while humidity and thunderstorms are 1961-1990 normals.