San Francisco Weather in December

Overall, December has the rainiest and cloudiest weather in San Francisco, California. But total rainfall for the month varies widely from year to year.

This page gives detailed information on the typical December temperature, precipitation, sun, humidity, wind and storms for San Francisco.

The temperature, rainfall, sunshine and wind speed numbers here are historical averages based on climate data gathered in downtown San Francisco near the corner of Buchanan and Hermann Streets. The rest of the measurements are averages at the San Francisco International Airport, located south of the city center.

Temperature Weather iconTemperature

57 °F December average high 14 °C
46 °F December average low 8 °C

In most years, San Francisco averages a daily maximum temperature for December that's between 55 and 59 degrees Fahrenheit (13 to 15 degrees Celsius). The minimum temperature usually falls between 44 and 48 °F (7 to 9 °C).

The days at San Francisco continue to cool down during December. By the end of the month, the temperature has dropped around 3 °F (2 °C) below what it was at the start.

8 days 60 °F max. or more (16 °C)
26 days 50 °F min. or less (10 °C)

San Francisco warms up to at least 50 °F (10 °C) on most days in December. Temperatures of 70 °F (21 °C) or above rarely occur here this month.

The thermometer dips to 40 °F (4 °C) or below on 2 nights. December is when the temperature is most likely to drop to freezing, but that only happens once a decade on average.

Rainy Weather iconRain

4.6 in total precipitation 116 mm
12 days of rain

December is the rainiest month in San Francisco. Half the time, the city receives 2 to 8 inches (56 to 193 mm) of rainfall in December. One in four years has drier weather, while another one in four is wetter.

Sunny Weather iconSun

53 % sunshine
9 days clear skies

The sun's rays reach the ground in San Francisco during 53 percent of daylight hours on average in December, for a total of 158 hours in the month. Typically on 9 days this month the sky is mainly clear, with at most 30 percent cloud cover. December is the cloudiest month for San Francisco.

Sunlight in December at San Francisco averages 9 hours and 35 minutes a day. The shortest days of the year, from around December 17th to 24th, last 9 hours and 33 minutes from sunrise to sunset.

Humid Weather iconHumidity

78 % December average humidity

The relative humidity in San Francisco during December usually peaks at 85 percent in the morning then drops to 67 percent by late afternoon.

Local Time1 am4 am7 am10 am1 pm4 pm7 pm10 pm
Humidity % 82 85 85 77 68 67 76 80

Windy Weather iconWind

6.5 mph December wind speed average 10.5 kph

December is less windy than most other months in San Francisco.

Stormy Weather iconStorms

3 days rainfall of 0.5 inches (13 mm) or more
0 days with thunderstorms in December

About once every five years, a thunderstorm passes through San Francisco in December.

Reference

These weather data are long-term historical averages provided by the National Climatic Data Center of the United States. The temperature and precipitation numbers are 1981-2010 normals while the humidity and thunderstorm statistics are 1961-1990 normals.

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