December is one of the cooler months of the year in San Francisco, with average highs near 13.6°C and lows around 6.4°C (mean 10°C). It is a relatively wet time of year, averaging 122 mm of rainfall and 82% relative humidity across the period.
December is one of the cooler months of the year in San Francisco. Across 45 years of records, the warmest December in San Francisco was 2014 — when the month averaged 12.1°C — while the coldest was 1990 at 8°C. Typical December days reach 13.6°C with nights near 6.4°C. The long-term trend is warming, about 0.2°C per decade.
December is a relatively wet time of year in San Francisco, averaging 122 mm of rainfall. The wettest December on record was 2005 with 318 mm, while the driest was 2017 at 3 mm.
Relative humidity in San Francisco during December averages 82%. The most humid December was 1983 at 90%, and the least humid was 2013 at 67%.
December receives about 2.2 kWh/m²/day of solar energy in San Francisco. The sunniest Decembers were 1990 and 2013 at 2.7 kWh/m²/day, and the cloudiest was 2010 at 1.7.
Average wind speed in San Francisco during December is 2.3 m/s. The windiest December was 1987 at 3 m/s, while the calmest was 1986 at 1.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 9.9°C | 9.7°C | 9.8°C | 10.2°C | 10.6°C | +0.7°C |
| Avg High | 13.6°C | 13.5°C | 13.1°C | 13.7°C | 14.1°C | +0.5°C |
| Avg Low | 6.3°C | 5.8°C | 6.4°C | 6.7°C | 7.1°C | +0.8°C |
| Avg Rain | 99 mm | 103 mm | 165 mm | 109 mm | 137 mm | +37 mm |
December temperatures in San Francisco have risen by about 0.8°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -3°C (1990) to a record high of 20.3°C (1989).
Rainfall in December is a relatively wet time of year, averaging 122 mm, with a wettest year of 318 mm.
A quieter season to visit San Francisco
If your dates are flexible, the more temperate months of September and August tend to be the most comfortable for visiting San Francisco. That said, December — with days averaging 13.6°C and nights around 6.4°C (mean 10°C) and higher rainfall (122 mm) — can still be rewarding for travellers who don't mind the cooler conditions, and often means fewer crowds.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 14.0°C | 10.8°C | 7.6°C | 16.9°C | 4.7°C | 108 mm | 89% | 2.2 m/s | — |
| 2024 | 14.8°C | 11.3°C | 7.8°C | 18.8°C | 3.7°C | 133 mm | 88% | 2.1 m/s | 2.2 |
| 2023 | 15.5°C | 11.9°C | 8.4°C | 18.6°C | 4.6°C | 112 mm | 86% | 2 m/s | 2 |
| 2022 | 12.6°C | 9.2°C | 5.8°C | 15.2°C | 0.9°C | 233 mm | 86% | 2.1 m/s | 2.1 |
| 2021 | 12.4°C | 9.4°C | 6.4°C | 19.3°C | 3.0°C | 191 mm | 89% | 2.3 m/s | 2 |
| 2020 | 15.1°C | 10.8°C | 6.5°C | 20.2°C | 2.9°C | 43 mm | 77% | 2 m/s | 2.5 |
| 2019 | 13.7°C | 11.0°C | 8.2°C | 16.5°C | 4.1°C | 136 mm | 89% | 2.2 m/s | 1.8 |
| 2018 | 14.2°C | 10.7°C | 7.2°C | 16.4°C | 4.1°C | 63 mm | 82% | 2.2 m/s | 2.2 |
| 2017 | 15.1°C | 10.6°C | 6.2°C | 17.3°C | 4.0°C | 3 mm | 71% | 2 m/s | 2.6 |
| 2016 | 12.6°C | 9.2°C | 5.8°C | 16.6°C | 1.1°C | 108 mm | 84% | 2.3 m/s | 2.3 |
| 2015 | 13.1°C | 9.9°C | 6.8°C | 17.3°C | 1.1°C | 93 mm | 82% | 2.4 m/s | 2.2 |
| 2014 🔥 | 14.8°C | 12.1°C | 9.4°C | 18.5°C | 3.1°C | 295 mm | 88% | 2.3 m/s | 1.9 |
| 2013 | 14.1°C | 9.2°C | 4.2°C | 19.8°C | -0.8°C | 15 mm | 67% | 2 m/s | 2.7 |
| 2012 | 12.7°C | 9.8°C | 6.8°C | 17.1°C | 1.7°C | 188 mm | 84% | 2.5 m/s | 2.1 |
| 2011 | 14.1°C | 9.4°C | 4.8°C | 19.6°C | 1.3°C | 5 mm | 70% | 1.8 m/s | 2.6 |
| 2010 | 12.9°C | 10.1°C | 7.4°C | 17.5°C | 1.6°C | 185 mm | 89% | 2.1 m/s | 1.7 |
| 2009 | 11.8°C | 8.4°C | 5.1°C | 16.5°C | -0.6°C | 77 mm | 84% | 2 m/s | 2 |
| 2008 | 12.4°C | 8.7°C | 5.0°C | 17.3°C | 0.8°C | 63 mm | 81% | 2.1 m/s | 2.2 |
| 2007 | 12.4°C | 8.8°C | 5.1°C | 18.0°C | 2.0°C | 96 mm | 80% | 2.3 m/s | 2.3 |
| 2006 | 13.3°C | 9.4°C | 5.4°C | 17.0°C | 0.3°C | 113 mm | 79% | 2.3 m/s | 2.2 |
| 2005 🌧️ | 13.8°C | 10.7°C | 7.6°C | 19.4°C | 2.0°C | 318 mm | 86% | 2.4 m/s | 1.8 |
| 2004 | 14.0°C | 10.3°C | 6.7°C | 16.9°C | 2.8°C | 209 mm | 83% | 2.2 m/s | 2.3 |
| 2003 | 13.1°C | 10.3°C | 7.5°C | 17.0°C | 3.9°C | 207 mm | 87% | 2.4 m/s | 1.9 |
| 2002 | 13.9°C | 11.1°C | 8.2°C | 17.6°C | 3.7°C | 315 mm | 86% | 2.7 m/s | 1.9 |
| 2001 | 12.3°C | 9.8°C | 7.2°C | 15.4°C | 3.0°C | 234 mm | 89% | 2.5 m/s | 1.8 |
| 2000 | 14.4°C | 10.3°C | 6.3°C | 17.5°C | 2.9°C | 21 mm | 79% | 1.9 m/s | 2.3 |
| 1999 | 15.3°C | 10.4°C | 5.6°C | 19.2°C | 3.2°C | 12 mm | 75% | 2 m/s | 2.6 |
| 1998 | 12.1°C | 8.3°C | 4.4°C | 18.7°C | -2.4°C | 32 mm | 80% | 2.1 m/s | 2.4 |
| 1997 | 13.7°C | 9.9°C | 6.1°C | 16.2°C | 0.7°C | 77 mm | 79% | 2.8 m/s | 2.4 |
| 1996 | 13.9°C | 11.1°C | 8.3°C | 16.1°C | 3.6°C | 252 mm | 87% | 2.7 m/s | 1.9 |
| 1995 | 14.4°C | 11.2°C | 7.9°C | 18.4°C | 3.0°C | 203 mm | 87% | 2.2 m/s | 2 |
| 1994 | 12.0°C | 8.5°C | 5.0°C | 14.7°C | 0.5°C | 90 mm | 85% | 2 m/s | 2.2 |
| 1993 | 13.7°C | 9.8°C | 5.9°C | 18.4°C | 0.9°C | 71 mm | 81% | 2.3 m/s | 2.3 |
| 1992 | 12.7°C | 9.2°C | 5.7°C | 15.4°C | 0.2°C | 182 mm | 82% | 2.9 m/s | 2.1 |
| 1991 | 14.5°C | 10.2°C | 6.0°C | 16.8°C | 2.6°C | 72 mm | 74% | 2.2 m/s | 2.3 |
| 1990 ❄️ | 12.7°C | 8.0°C | 3.3°C | 19.7°C | -3.0°C | 38 mm | 68% | 2.3 m/s | 2.7 |
| 1989 | 15.9°C | 11.1°C | 6.3°C | 20.3°C | 3.0°C | 3 mm | 73% | 1.8 m/s | 2.6 |
| 1988 | 13.8°C | 9.8°C | 5.8°C | 19.7°C | -0.7°C | 93 mm | 76% | 2.4 m/s | 2.2 |
| 1987 | 12.4°C | 9.3°C | 6.2°C | 17.2°C | 0.9°C | 136 mm | 80% | 3 m/s | 2 |
| 1986 | 15.0°C | 10.6°C | 6.2°C | 18.9°C | 2.7°C | 47 mm | 75% | 1.7 m/s | 2.2 |
| 1985 | 13.0°C | 8.8°C | 4.7°C | 15.5°C | -1.2°C | 70 mm | 83% | 2.2 m/s | 2.3 |
| 1984 | 12.4°C | 8.7°C | 5.1°C | 16.0°C | 1.4°C | 53 mm | 83% | 2.3 m/s | 2.3 |
| 1983 | 13.1°C | 10.7°C | 8.2°C | 16.3°C | 3.5°C | 217 mm | 90% | 2.6 m/s | — |
| 1982 | 12.9°C | 9.4°C | 6.0°C | 16.4°C | 0.6°C | 97 mm | 83% | 2.6 m/s | — |
| 1981 | 14.1°C | 11.1°C | 8.2°C | 17.8°C | 5.3°C | 180 mm | 88% | 2.3 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 13.6°C with lows near 6.4°C (mean 10°C), based on 45 years of NASA POWER data.
December averages 122 mm of rainfall in San Francisco, a relatively wet time of year. The wettest on record was 318 mm in 2005.
The hottest December reached 20.3°C in 1989. The coldest dipped to -3°C in 1990.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 0.8°C. Daytime highs moved from 13.1°C to 13.9°C and overnight lows from 6.4°C to 7.2°C over the same span.
December is one of the cooler months of the year in San Francisco and a relatively wet time of year, so plan for around 13.6°C daytime highs and 6.4°C at night.
Not quite — December is the 2nd coolest month in San Francisco, averaging 10°C.
For December in San Francisco, pack warm layers and a jacket for chilly mornings, with typical highs of 13.6°C and lows of 6.4°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 82% — quite humid.
Average wind speed in December is 2.3 m/s. The windiest December on record averaged 3 m/s (1987).
The wettest December on record was 2005 with 318 mm. On average, December sees 122 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in San Francisco behaves each December, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for December specifically, along with year-by-year records and how the month has changed over the decades.
