With a population of around 67,300, South San Francisco sits in California, United States. The city operates in the Pacific Time Zone.
In 2025, South San Francisco recorded an average annual temperature of 56°F — about 3.1°F below the 30-year normal of 59°F. The hottest day reached 86°F in September; the coldest was 39°F in January. Total precipitation was 20 inches (near normal). The wettest month was February.
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