May is one of the warmer months of the year in Santa Rosa, with average highs near 23.3°C and lows around 9°C (mean 16.2°C). It is one of the drier months, averaging 23 mm of rainfall and 68% relative humidity across the period.
May is one of the warmer months of the year in Santa Rosa. Across 45 years of records, the warmest May in Santa Rosa was 2001 — when the month averaged 20.2°C — while the coldest was 1998 at 12°C. Typical May days reach 23.3°C with nights near 9°C. The long-term May temperature trend is broadly flat.
May is one of the drier months in Santa Rosa, averaging 23 mm of rainfall. The wettest May on record was 1998 with 105 mm, while the driest was 2001 at 0 mm.
Relative humidity in Santa Rosa during May averages 68%. The most humid May was 1998 at 82%, and the least humid was 2021 at 48%.
May receives about 7.2 kWh/m²/day of solar energy in Santa Rosa. The sunniest May was 2021 at 8.2 kWh/m²/day, and the cloudiest was 1998 at 5.5.
Average wind speed in Santa Rosa during May is 1.8 m/s. The windiest May was 2022 at 2.2 m/s, while the calmest was 1995 at 1.3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 16.2°C | 15.7°C | 16.5°C | 15.5°C | 17.2°C | +1°C |
| Avg High | 23.7°C | 22.4°C | 23.7°C | 22.4°C | 24.9°C | +1.2°C |
| Avg Low | 8.7°C | 8.9°C | 9.3°C | 8.7°C | 9.6°C | +0.9°C |
| Avg Rain | 8 mm | 42 mm | 26 mm | 19 mm | 13 mm | +5 mm |
May temperatures in Santa Rosa have risen by about 1°C between 1981–1985 and 2021–2025.
May has ranged from a record low of 1.8°C (2010) to a record high of 39°C (2021).
Rainfall in May is one of the drier months, averaging 23 mm, with a wettest year of 105 mm.
A good time to visit Santa Rosa
May is a good time to visit Santa Rosa, with days averaging 23.3°C and nights around 9°C (mean 16.2°C, close to Santa Rosa's yearly average) and low rainfall. September and July 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 | 25.4°C | 17.6°C | 9.9°C | 36.4°C | 6.6°C | 3 mm | 64% | 1.9 m/s | 8 |
| 2024 | 24.3°C | 16.7°C | 9.1°C | 31.5°C | 4.1°C | 22 mm | 66% | 1.8 m/s | 7.9 |
| 2023 | 20.8°C | 15.0°C | 9.1°C | 28.5°C | 6.3°C | 23 mm | 79% | 1.6 m/s | 6.7 |
| 2022 | 25.1°C | 17.0°C | 9.0°C | 35.0°C | 2.7°C | 3 mm | 58% | 2.2 m/s | 7.7 |
| 2021 | 28.2°C | 19.2°C | 10.2°C | 39.0°C | 5.9°C | 0 mm | 48% | 2.1 m/s | 8.2 |
| 2020 | 25.4°C | 17.8°C | 10.2°C | 37.0°C | 5.1°C | 27 mm | 62% | 1.9 m/s | 7.1 |
| 2019 | 19.9°C | 14.2°C | 8.5°C | 26.4°C | 5.1°C | 83 mm | 80% | 1.8 m/s | 6.4 |
| 2018 | 23.6°C | 16.4°C | 9.3°C | 33.1°C | 5.6°C | 4 mm | 69% | 2 m/s | 7.2 |
| 2017 | 22.2°C | 15.7°C | 9.3°C | 28.9°C | 3.9°C | 2 mm | 74% | 1.8 m/s | 7.5 |
| 2016 | 22.9°C | 16.4°C | 10.0°C | 33.8°C | 6.7°C | 11 mm | 72% | 1.6 m/s | 6.8 |
| 2015 | 22.2°C | 15.4°C | 8.6°C | 27.8°C | 6.6°C | 4 mm | 69% | 2 m/s | 7 |
| 2014 | 26.3°C | 18.1°C | 10.0°C | 33.7°C | 5.7°C | 1 mm | 57% | 1.9 m/s | 7.9 |
| 2013 | 25.7°C | 17.6°C | 9.6°C | 32.7°C | 4.7°C | 4 mm | 57% | 2 m/s | 7.5 |
| 2012 | 24.2°C | 16.5°C | 8.8°C | 34.3°C | 4.9°C | 3 mm | 65% | 1.9 m/s | 7.9 |
| 2011 | 18.4°C | 12.6°C | 6.7°C | 26.5°C | 3.6°C | 41 mm | 76% | 2 m/s | 6.9 |
| 2010 | 18.6°C | 12.5°C | 6.3°C | 25.1°C | 1.8°C | 39 mm | 77% | 1.8 m/s | 6.7 |
| 2009 | 24.8°C | 17.2°C | 9.7°C | 34.1°C | 5.7°C | 47 mm | 67% | 1.7 m/s | 7.1 |
| 2008 | 24.7°C | 17.0°C | 9.3°C | 35.8°C | 4.3°C | 2 mm | 62% | 1.9 m/s | 7.5 |
| 2007 | 25.1°C | 17.1°C | 9.1°C | 30.6°C | 3.9°C | 12 mm | 62% | 1.9 m/s | 7.7 |
| 2006 | 22.3°C | 16.0°C | 9.6°C | 28.6°C | 5.8°C | 16 mm | 78% | 1.5 m/s | 7.3 |
| 2005 | 21.1°C | 15.1°C | 9.2°C | 27.5°C | 5.1°C | 95 mm | 81% | 1.7 m/s | 6.7 |
| 2004 | 23.6°C | 16.3°C | 9.0°C | 30.6°C | 5.8°C | 2 mm | 70% | 1.8 m/s | 7.7 |
| 2003 | 21.6°C | 15.2°C | 8.7°C | 30.5°C | 3.3°C | 26 mm | 76% | 1.6 m/s | 7.2 |
| 2002 | 22.1°C | 15.0°C | 7.9°C | 31.4°C | 4.3°C | 25 mm | 70% | 1.7 m/s | 7.6 |
| 2001 🔥 | 29.0°C | 20.2°C | 11.5°C | 37.5°C | 7.2°C | 0 mm | 53% | 1.9 m/s | 8 |
| 2000 | 22.5°C | 15.9°C | 9.3°C | 33.1°C | 2.3°C | 34 mm | 72% | 1.7 m/s | 7 |
| 1999 | 22.4°C | 14.7°C | 7.0°C | 30.6°C | 3.1°C | 4 mm | 70% | 1.8 m/s | 7.7 |
| 1998 ❄️ 🌧️ | 17.0°C | 12.0°C | 7.0°C | 21.2°C | 2.6°C | 105 mm | 82% | 1.6 m/s | 5.5 |
| 1997 | 27.4°C | 19.3°C | 11.1°C | 34.7°C | 3.5°C | 15 mm | 62% | 1.6 m/s | 7.7 |
| 1996 | 21.7°C | 15.3°C | 8.8°C | 28.7°C | 5.0°C | 76 mm | 74% | 1.6 m/s | 7 |
| 1995 | 19.9°C | 14.4°C | 8.8°C | 27.1°C | 4.2°C | 34 mm | 81% | 1.3 m/s | 6.7 |
| 1994 | 23.7°C | 16.5°C | 9.2°C | 32.7°C | 5.4°C | 34 mm | 69% | 1.5 m/s | 6.5 |
| 1993 | 20.0°C | 14.4°C | 8.8°C | 25.7°C | 4.0°C | 46 mm | 80% | 1.7 m/s | 6.2 |
| 1992 | 26.8°C | 19.2°C | 11.6°C | 32.7°C | 8.1°C | 1 mm | 66% | 1.5 m/s | 7.5 |
| 1991 | 21.8°C | 14.8°C | 7.8°C | 29.4°C | 4.0°C | 8 mm | 67% | 1.7 m/s | 6.9 |
| 1990 | 23.4°C | 16.2°C | 9.1°C | 31.8°C | 4.7°C | 99 mm | 63% | 2 m/s | 6.7 |
| 1989 | 23.6°C | 16.2°C | 8.8°C | 29.7°C | 5.9°C | 3 mm | 66% | 1.7 m/s | 7.3 |
| 1988 | 22.9°C | 15.3°C | 7.7°C | 32.1°C | 2.2°C | 25 mm | 63% | 1.8 m/s | 7.1 |
| 1987 | 27.1°C | 19.1°C | 11.0°C | 34.7°C | 4.8°C | 3 mm | 58% | 1.6 m/s | 7.3 |
| 1986 | 21.8°C | 14.9°C | 8.0°C | 28.3°C | 2.1°C | 12 mm | 73% | 1.6 m/s | 7 |
| 1985 | 23.3°C | 15.6°C | 7.8°C | 29.7°C | 4.8°C | 1 mm | 61% | 1.8 m/s | 7.5 |
| 1984 | 25.3°C | 17.2°C | 9.2°C | 35.1°C | 3.5°C | 4 mm | 62% | 1.9 m/s | 7.5 |
| 1983 | 21.2°C | 14.6°C | 8.0°C | 27.8°C | 1.9°C | 11 mm | 77% | 1.7 m/s | — |
| 1982 | 22.8°C | 15.8°C | 8.7°C | 29.6°C | 5.2°C | 0 mm | 73% | 1.5 m/s | — |
| 1981 | 25.5°C | 17.3°C | 9.1°C | 32.7°C | 3.4°C | 11 mm | 59% | 1.9 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 23.3°C with lows near 9°C (mean 16.2°C), based on 45 years of NASA POWER data.
May averages 23 mm of rainfall in Santa Rosa, one of the drier months. The wettest on record was 105 mm in 1998.
The hottest May reached 39°C in 2021. The coldest dipped to 1.8°C in 2010.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 1°C. Daytime highs moved from 23.6°C to 24.8°C and overnight lows from 8.6°C to 9.5°C over the same span.
May is one of the warmer months of the year in Santa Rosa and one of the drier months, so plan for around 23.3°C daytime highs and 9°C at night.
Not quite — May is the 7th coolest month in Santa Rosa, averaging 16.2°C.
For May in Santa Rosa, pack light layers you can adjust through the day, with typical highs of 23.3°C and lows of 9°C.
Relative humidity in May averages 68% — moderately humid.
Average wind speed in May is 1.8 m/s. The windiest May on record averaged 2.2 m/s (2022).
The wettest May on record was 1998 with 105 mm. On average, May sees 23 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 Santa Rosa 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.
