South San Francisco (CA) Weather & Climate: Best Time to Visit

In South San Francisco, seasonal changes bring about a moderate variation in temperatures. Typically, average maximum daytime temperatures range from a comfortable 23°C (73°F) in September to a moderate 14°C (57°F) in the coolest month, December.

Nights vary from 14°C (57°F) in September to around 7°C (45°F) during the colder months.

Check out our detailed temperature page for more information.

Temperature ranges by month

With annual rainfall averaging 488 mm (19 in), South San Francisco maintains relatively low precipitation levels throughout the seasons. The climate in South San Francisco shows significant variation throughout the year. Expect high rainfall in December, the wettest month, with an average of 114 mm (4.5 in) of precipitation over 13 rainy days.

In contrast, the driest month July offers drier and sunnier days, with around 0.5 mm (0.02 in) of rainfall over a single rainy day. For more details, please visit our South San Francisco Precipitation page.

The mean monthly precipitation over the year, including rain, hail, and snow

The average number of days each month with precipitation

For those who appreciate different seasons, South San Francisco serves as an ideal destination. Expect longer, more sun-filled days in May with an average of 10.8 hours of sunshine daily, and embrace the darker days in December, offering only 5.3 hours of daily sunlight.

Visit our detailed sunshine hours page for more information.

Monthly hours of sunshine

Daily hours of sunshine

Daily percentage of sunshine

The mean water temperature over the year ranges from 12°C (54°F) in January to 14°C (57°F) in June.

Water temperature over the year

The relative humidity is high throughout the year in South San Francisco.

The city experiences its highest humidity in January, reaching 80%. In June, the humidity drops to its lowest level at 71%. What does this mean? Read our detailed page on humidity levels for further details.

Relative humidity over the year

The average wind speed over the year ranges from 3 m/s (6 knots) to 7 m/s (14 knots). It is lower in January, November and December and higher in June and July. What does this mean?

The mean monthly wind speed over the year (meters per second)