May is close to San Francisco's year-round average, with average highs near 19.4°C and lows around 9.8°C (mean 14.6°C). It is one of the drier months, averaging 19 mm of rainfall and 77% relative humidity across the period.
May is close to San Francisco's year-round average. Across 45 years of records, the warmest May in San Francisco was 1997 — when the month averaged 17.1°C — while the coldest was 2010 at 12.3°C. Typical May days reach 19.4°C with nights near 9.8°C. The long-term May temperature trend is broadly flat.
May is one of the drier months in San Francisco, averaging 19 mm of rainfall. The wettest May on record was 1998 with 85 mm, while the driest were 1982, 2001 and 2021 at 0 mm.
Relative humidity in San Francisco during May averages 77%. The most humid May was 2005 at 85%, and the least humid was 2021 at 68%.
May receives about 6.7 kWh/m²/day of solar energy in San Francisco. The sunniest Mays were 2022 and 2025 at 7.5 kWh/m²/day, and the cloudiest was 2019 at 5.7.
Average wind speed in San Francisco during May is 2.5 m/s. The windiest May was 2021 at 3.1 m/s, while the calmest was 1992 at 1.9 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 14.7°C | 14.5°C | 14.6°C | 14.2°C | 15.3°C | +0.6°C |
| Avg High | 19.8°C | 19.1°C | 19.3°C | 18.6°C | 20.4°C | +0.6°C |
| Avg Low | 9.5°C | 9.8°C | 9.8°C | 9.8°C | 10.1°C | +0.6°C |
| Avg Rain | 7 mm | 34 mm | 22 mm | 16 mm | 11 mm | +4 mm |
May temperatures in San Francisco have risen by about 0.4°C between 1981–1985 and 2021–2025.
May has ranged from a record low of 5°C (2010) to a record high of 33.7°C (2001).
Rainfall in May is one of the drier months, averaging 19 mm, with a wettest year of 85 mm.
Daytime highs and overnight lows have shifted differently — highs fell about 0.1°C per decade while lows rose 0.1°C per decade, narrowing the gap between day and night.
A good time to visit San Francisco
May is a good time to visit San Francisco, with days averaging 19.4°C and nights around 9.8°C (mean 14.6°C, close to San Francisco's yearly average) and low rainfall. September and August are marginally more temperate, but May still suits most travellers.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 20.7°C | 15.5°C | 10.3°C | 28.2°C | 8.9°C | 3 mm | 75% | 2.8 m/s | 7.5 |
| 2024 | 20.2°C | 15.0°C | 9.8°C | 25.7°C | 7.5°C | 21 mm | 76% | 2.6 m/s | 7.2 |
| 2023 | 17.6°C | 13.8°C | 9.9°C | 25.4°C | 8.3°C | 19 mm | 84% | 2.4 m/s | 5.8 |
| 2022 | 20.9°C | 15.3°C | 9.6°C | 30.2°C | 6.1°C | 2 mm | 70% | 2.9 m/s | 7.5 |
| 2021 | 21.1°C | 15.6°C | 10.0°C | 27.2°C | 7.7°C | 0 mm | 68% | 3.1 m/s | 7.2 |
| 2020 | 21.6°C | 16.3°C | 11.0°C | 29.9°C | 7.6°C | 18 mm | 73% | 2.5 m/s | 7 |
| 2019 | 17.7°C | 13.9°C | 10.0°C | 22.2°C | 7.6°C | 70 mm | 83% | 2.7 m/s | 5.7 |
| 2018 | 19.0°C | 14.6°C | 10.2°C | 27.8°C | 7.8°C | 4 mm | 79% | 2.8 m/s | 6.5 |
| 2017 | 19.2°C | 14.6°C | 10.0°C | 26.0°C | 7.3°C | 3 mm | 80% | 2.5 m/s | 6.9 |
| 2016 | 19.6°C | 15.2°C | 10.8°C | 26.1°C | 9.5°C | 8 mm | 79% | 2.2 m/s | 6.3 |
| 2015 | 17.1°C | 13.4°C | 9.7°C | 22.2°C | 8.0°C | 7 mm | 81% | 2.6 m/s | 5.8 |
| 2014 | 21.3°C | 16.1°C | 10.9°C | 29.8°C | 8.3°C | 2 mm | 70% | 2.6 m/s | 7.3 |
| 2013 | 20.6°C | 15.4°C | 10.2°C | 28.4°C | 7.1°C | 4 mm | 70% | 2.7 m/s | 7 |
| 2012 | 19.0°C | 14.1°C | 9.2°C | 25.3°C | 6.9°C | 2 mm | 75% | 2.7 m/s | 7.2 |
| 2011 | 16.4°C | 12.4°C | 8.4°C | 24.1°C | 6.6°C | 30 mm | 80% | 2.9 m/s | 6.8 |
| 2010 ❄️ | 16.4°C | 12.3°C | 8.1°C | 21.5°C | 5.0°C | 30 mm | 81% | 2.6 m/s | 6.8 |
| 2009 | 19.3°C | 14.4°C | 9.5°C | 28.9°C | 7.5°C | 35 mm | 79% | 2.2 m/s | 5.9 |
| 2008 | 19.6°C | 14.5°C | 9.4°C | 33.6°C | 5.8°C | 3 mm | 74% | 2.5 m/s | 6.7 |
| 2007 | 19.3°C | 14.3°C | 9.4°C | 29.4°C | 7.3°C | 12 mm | 74% | 2.5 m/s | 6.7 |
| 2006 | 18.9°C | 14.5°C | 10.0°C | 25.3°C | 8.5°C | 13 mm | 84% | 2.3 m/s | 7 |
| 2005 | 18.7°C | 14.7°C | 10.7°C | 23.4°C | 8.2°C | 74 mm | 85% | 2.4 m/s | 6.5 |
| 2004 | 18.9°C | 14.4°C | 9.9°C | 23.8°C | 8.6°C | 3 mm | 79% | 2.6 m/s | 7.3 |
| 2003 | 18.5°C | 13.9°C | 9.4°C | 25.8°C | 6.4°C | 25 mm | 81% | 2.4 m/s | 6.7 |
| 2002 | 17.9°C | 13.3°C | 8.6°C | 24.7°C | 6.6°C | 23 mm | 79% | 2.4 m/s | 7 |
| 2001 | 23.0°C | 16.8°C | 10.6°C | 33.7°C | 8.6°C | 0 mm | 69% | 2.2 m/s | 7.3 |
| 2000 | 19.3°C | 14.7°C | 10.2°C | 29.2°C | 6.3°C | 36 mm | 79% | 2.6 m/s | 6.9 |
| 1999 | 17.5°C | 12.7°C | 7.8°C | 25.7°C | 5.3°C | 3 mm | 79% | 2.7 m/s | 6.7 |
| 1998 🌧️ | 16.0°C | 12.7°C | 9.4°C | 19.9°C | 6.7°C | 85 mm | 83% | 2.5 m/s | 6.4 |
| 1997 🔥 | 22.6°C | 17.1°C | 11.7°C | 31.4°C | 5.8°C | 12 mm | 75% | 2.1 m/s | 7.3 |
| 1996 | 19.1°C | 14.5°C | 9.8°C | 24.1°C | 7.5°C | 65 mm | 80% | 2.3 m/s | 7.1 |
| 1995 | 17.7°C | 13.5°C | 9.4°C | 23.1°C | 7.4°C | 27 mm | 84% | 2 m/s | 6.1 |
| 1994 | 19.4°C | 14.5°C | 9.5°C | 27.6°C | 7.4°C | 32 mm | 78% | 2.1 m/s | 6.5 |
| 1993 | 18.5°C | 14.5°C | 10.5°C | 24.7°C | 7.0°C | 32 mm | 82% | 2.2 m/s | 6.6 |
| 1992 | 22.4°C | 17.0°C | 11.6°C | 26.0°C | 9.7°C | 1 mm | 76% | 1.9 m/s | 6.3 |
| 1991 | 18.3°C | 13.4°C | 8.4°C | 23.6°C | 6.4°C | 8 mm | 75% | 2.4 m/s | 6.4 |
| 1990 | 19.6°C | 14.8°C | 10.0°C | 27.5°C | 8.2°C | 78 mm | 73% | 2.5 m/s | 6.4 |
| 1989 | 19.7°C | 14.7°C | 9.8°C | 27.1°C | 7.9°C | 3 mm | 76% | 2.5 m/s | 6.7 |
| 1988 | 18.9°C | 13.9°C | 8.9°C | 28.8°C | 5.5°C | 22 mm | 73% | 2.6 m/s | 7 |
| 1987 | 22.0°C | 16.5°C | 10.9°C | 29.6°C | 7.8°C | 2 mm | 71% | 2.4 m/s | 6.6 |
| 1986 | 18.9°C | 13.9°C | 9.0°C | 24.1°C | 5.1°C | 10 mm | 79% | 2.3 m/s | 6.5 |
| 1985 | 18.9°C | 13.9°C | 8.8°C | 24.8°C | 6.6°C | 3 mm | 74% | 2.5 m/s | 6.9 |
| 1984 | 20.9°C | 15.3°C | 9.7°C | 30.9°C | 6.3°C | 4 mm | 71% | 2.6 m/s | 7.3 |
| 1983 | 18.7°C | 14.1°C | 9.5°C | 24.4°C | 5.9°C | 10 mm | 80% | 2.5 m/s | — |
| 1982 | 19.6°C | 14.3°C | 9.0°C | 26.8°C | 7.0°C | 0 mm | 80% | 2.1 m/s | — |
| 1981 | 20.9°C | 15.3°C | 9.7°C | 26.4°C | 6.2°C | 10 mm | 71% | 2.8 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 19.4°C with lows near 9.8°C (mean 14.6°C), based on 45 years of NASA POWER data.
May averages 19 mm of rainfall in San Francisco, one of the drier months. The wettest on record was 85 mm in 1998.
The hottest May reached 33.7°C in 2001. The coldest dipped to 5°C in 2010.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 0.4°C. Daytime highs moved from 19.8°C to 20.1°C and overnight lows from 9.3°C to 9.9°C over the same span.
May is close to San Francisco's year-round average and one of the drier months, so plan for around 19.4°C daytime highs and 9.8°C at night.
Not quite — May is the 7th coolest month in San Francisco, averaging 14.6°C.
For May in San Francisco, pack light layers you can adjust through the day, with typical highs of 19.4°C and lows of 9.8°C.
Relative humidity in May averages 77% — quite humid.
Average wind speed in May is 2.5 m/s. The windiest May on record averaged 3.1 m/s (2021).
The wettest May on record was 1998 with 85 mm. On average, May sees 19 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 May, 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 May specifically, along with year-by-year records and how the month has changed over the decades.
