Climate averages 1991–2020
San Francisco weather
in December.
A cool, wet month: the coolest and the 10th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a cool month in San Francisco: daytime highs average 13.5°C and nights cool to about 6.3°C. By daytime temperature it is the coolest month of the year.
Expect about 108 mm of rain on roughly 10 days, which makes December a wet month (the 10th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 9 h 36 min on an average December day.
The nearest other city in this atlas is Daly City (9 km away). In December its highs average 12.6°C, 0.9°C cooler than San Francisco, with 108 mm of rain.
Among the 498 cities listed in the United States, San Francisco ranks joint 198th of 498 for the warmest December highs and joint 422nd of 498 for the driest December (rainfall, lowest first). The mean December high of those 498 cities is 10.5°C; San Francisco is 2.9°C warmer than that mean.
From December to January, average highs rise by 0.1°C to 13.6°C, and monthly rainfall rises from 108 mm to 109 mm.
The annual picture
December in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
San Francisco climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 13.6°C6.1°C | 6.1°C | 109 | 10.1 | 9.910 h |
| February | 14.6°C7.0°C | 7.0°C | 113 | 9.5 | 10.811 h |
| March | 15.7°C8.1°C | 8.1°C | 81 | 9.3 | 11.912 h |
| April | 17.0°C8.8°C | 8.8°C | 37 | 5.0 | 13.113 h |
| May | 18.8°C10.4°C | 10.4°C | 18 | 2.8 | 14.214 h |
| June | 21.0°C11.7°C | 11.7°C | 4.3 | 0.8 | 14.715 h |
| July | 21.5°C12.6°C | 12.6°C | 0.3 | 0.1 | 14.515 h |
| August | 22.1°C13.2°C | 13.2°C | 0.7 | 0.1 | 13.614 h |
| September | 22.7°C13.0°C | 13.0°C | 1.5 | 0.4 | 12.512 h |
| October | 21.0°C11.8°C | 11.8°C | 24 | 3.1 | 11.311 h |
| November | 16.6°C8.7°C | 8.7°C | 56 | 6.1 | 10.210 h |
| December, selected | 13.5°C6.3°C | 6.3°C | 108 | 10.1 | 9.610 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
December in nearby cities
- Daly City in DecemberUnited States · 9 kmHigh 12.6°C · Low 6.8°C · 108 mm rain
- Oakland in DecemberUnited States · 13 kmHigh 13.8°C · Low 6.0°C · 87 mm rain
- Berkeley in DecemberUnited States · 17 kmHigh 13.6°C · Low 5.7°C · 87 mm rain
- San Mateo in DecemberUnited States · 25 kmHigh 13.7°C · Low 7.2°C · 94 mm rain
- Hayward in DecemberUnited States · 32 kmHigh 13.8°C · Low 6.2°C · 81 mm rain
- Redwood City in DecemberUnited States · 36 kmHigh 13.8°C · Low 7.5°C · 94 mm rain
- San Ramon in DecemberUnited States · 39 kmHigh 13.6°C · Low 5.6°C · 81 mm rain
- Vallejo in DecemberUnited States · 39 kmHigh 13.9°C · Low 5.5°C · 95 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for San Francisco) is explained once on the San Francisco year overview and on the Sources, method and limits page.
Daly City lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.