San Francisco Weather in January
January has the coldest weather of the year for San Francisco, California. Yet the temperatures remain mild and well above freezing.
This page gives detailed information on the typical January 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.
|57 °F||January average high||14 °C|
|46 °F||January average low||8 °C|
In most years, San Francisco averages a daily maximum temperature for January that's between 55 and 59 degrees Fahrenheit (13 to 15 degrees Celsius). The minimum temperature usually falls between 44 and 48 °F (6 to 9 °C).
January is the coldest month overall for San Francisco and the 1st to 4th are its chilliest days. These, along with the last few days of December have daily highs averaging 56.0 °F (13.3 °C) and lows of 45.2 °F (7.3 °C).
|8 days||60 °F max. or more (16 °C)|
|27 days||50 °F min. or less (10 °C)|
Temperatures above 70 °F (21 °C) occur only rarely during January in San Francisco.
The thermometer dips to 40 °F (4 °C) or below on an average of 2 nights this month. But January does not normally get cold enough for frost.
|4.5 in||total precipitation||114 mm|
|12 days||of rain|
Half the time, San Francisco receives 2 to 7 inches (53 to 169 mm) of rainfall in January. One in four years has drier weather, while another one in four is wetter. None of the precipitation falls as snow.
|9 days||clear skies|
The sun's rays reach the ground in San Francisco during 56 percent of daylight hours on average in January, for a total of 172 hours in the month. Typically on 9 days this month the sky is mainly clear, with at most 30 percent cloud cover.
Sunlight in January at San Francisco lasts for 9 hours and 54 minutes a day on average. The shortest day of the month is the 1st with 9 hours and 37 minutes of daylight. By the end of the month, the days have lengthened to 10:18 from sunrise to sunset. These durations can vary by a minute or two from year to year.
|78 %||January average humidity|
The relative humidity in San Francisco during January usually peaks at 86 percent in the morning then drops to 66 percent by late afternoon. This is the most humid month for San Francisco.
|Local Time||1 am||4 am||7 am||10 am||1 pm||4 pm||7 pm||10 pm|
|6.7 mph||January wind speed average||10.8 kph|
January is less windy than most other months in San Francisco.
|3 days||rainfall of 0.5 inches (13 mm) or more|
|1 day||with thunderstorms in January|
San Francisco averages one January thunderstorm every two years.
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.