South San Francisco Climate by Month
South San Francisco, California, United States
Mild summers and mild winters, with most rain from December to March.
Mild summers and mild winters, with most rain from December to March: that's South San Francisco's climate in short. Expect highs of 74°F (24°C) in September and 58°F (15°C) in January, with the coldest nights (December) near 44°F (7°C). Of the 23 in (585 mm) of rain in a typical year, 73% falls from December to March. June to September are almost completely dry.
- Warmest month
- 74°F(24°C)
- Average high, September
- Coldest nights
- 44°F(7°C)
- Average low, December
- Rain per year
- 23 in(585 mm)
- Wettest: January
- Humidity
- 72%
- Sunniest: June
Best and worst months in South San Francisco
Best for weatherSeptember is the best time for weather in South San Francisco: highs near 74°F (24°C) and almost no rain.
Least pleasantDecember and January are the least pleasant; January is the coldest, with highs of only 58°F (15°C).
Comfort combines how close the afternoon high is to 75°F (24°C) with how much rain falls and how humid it is. See where the weather is best in September.
Temperature and rain through the year
Highs and lows (°F)
Average highAverage low
Rain (in per month)
South San Francisco weather by month
| Month | High | Low | Rain | Humidity | Sun |
|---|---|---|---|---|---|
| JanJanuary | 58°F(15°C) | 44°F(7°C) | 4.8 in(121 mm) | 78% | 1.9 |
| FebFebruary | 61°F(16°C) | 46°F(8°C) | 4.6 in(117 mm) | 72% | 2.7 |
| MarMarch | 64°F(18°C) | 47°F(8°C) | 3.1 in(80 mm) | 74% | 4.2 |
| AprApril | 66°F(19°C) | 48°F(9°C) | 1.5 in(38 mm) | 70% | 5.5 |
| MayMay | 68°F(20°C) | 50°F(10°C) | 0.6 in(16 mm) | 70% | 6.3 |
| JunJune | 71°F(22°C) | 53°F(12°C) | 0.2 in(5 mm) | 69% | 7.2 |
| JulJuly | 71°F(22°C) | 54°F(12°C) | 0.0 in(1 mm) | 72% | 7.0 |
| AugAugust | 72°F(22°C) | 55°F(13°C) | 0.0 in(1 mm) | 75% | 6.4 |
| SepSeptemberBest | 74°F(24°C) | 55°F(13°C) | 0.1 in(3 mm) | 68% | 5.3 |
| OctOctober | 72°F(22°C) | 51°F(11°C) | 1.2 in(30 mm) | 64% | 3.8 |
| NovNovember | 65°F(18°C) | 47°F(8°C) | 2.4 in(62 mm) | 72% | 2.5 |
| DecDecember | 59°F(15°C) | 44°F(7°C) | 4.4 in(111 mm) | 78% | 1.7 |
1991–2020 averages. Sun is solar radiation in kWh/m² per day. Highlighted: the most comfortable months.
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