South San Francisco (CA) Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit South San Francisco.
Climate overview of South San Francisco
Temperatures in South San Francisco, California, United States of America, shift moderately through the seasons. The warmest month is September at 23°C (73°F), and the coolest is December at 14°C (57°F).
The city tends toward dry conditions, with around 488 mm (19 in) of rainfall per year. It does, however, have a distinct dry season from May to October. The most sunshine falls in May, with an average of 10.8 hours of daily sunshine.
South San Francisco Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in South San Francisco - and find the best time to visit.
Monthly Temperature in South San Francisco
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
Rainfall in South San Francisco
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
Sunshine Hours in South San Francisco
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
Water Temperature in South San Francisco
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
Humidity in South San Francisco by Month
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
Wind Speed in South San Francisco
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)
Best Time to Visit South San Francisco
Monthly ratings reflect general weather comfort, based on daytime temperature and rainfall. Swimming and winter conditions are highlighted separately where relevant.
- Best overall: May, June, July, August, September and October
- Warmest weather: July, August, September and October
- Most sunshine: April, May, June and July
- Fewer rainy days: May, June, July, August and September
- Wettest months: January, February, March, April and December, when rainfall is highest.
- Seasonal pattern: A distinct dry season from May to October
Frequently asked questions about the climate in South San Francisco
What is the best time to visit South San Francisco?
May, June, July, August, September and October typically offer the most optimal weather in South San Francisco. In contrast, December tends to have less optimal conditions. South San Francisco has a distinct dry season from May to October.
What temperatures can I expect in South San Francisco?
Daytime highs range from 14°C (57°F) in December to 23°C (73°F) in September. Nighttime lows range from 7°C (45°F) to 14°C (57°F).
How much rain does South San Francisco get?
Annual rainfall is around 488 mm (19 in). December is the wettest month with 114 mm (4.5 in), while July is the driest with 0.5 mm (0.02 in).
How sunny is South San Francisco?
South San Francisco receives around 3,058 hours of sunshine per year. May is the sunniest month with 324 hours, while December is the cloudiest with just 160 hours. Overall, South San Francisco enjoys abundant sunshine.
South San Francisco 3-Day Forecast
South San Francisco (CA) 3-Day Forecast
South San Francisco on the map
South San Francisco is highlighted - select any city to see its climate.
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