May is one of the warmer months of the year in Sunnyvale, with average highs near 22.4°C and lows around 8.5°C (mean 15.5°C). It is one of the drier months, averaging 16 mm of rainfall and 73% relative humidity across the period.
May is one of the warmer months of the year in Sunnyvale. Across 45 years of records, the warmest May in Sunnyvale was 2001 — when the month averaged 19°C — while the coldest was 1998 at 12°C. Typical May days reach 22.4°C with nights near 8.5°C. The long-term May temperature trend is broadly flat.
May is one of the drier months in Sunnyvale, averaging 16 mm of rainfall. The wettest May on record was 1998 with 83 mm, while the driest were 1982 and 1992 at 0 mm.
Relative humidity in Sunnyvale during May averages 73%. The most humid May was 1998 at 83%, and the least humid was 2001 at 62%.
May receives about 6.7 kWh/m²/day of solar energy in Sunnyvale. 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 Sunnyvale during May is 2.5 m/s. The windiest May was 2021 at 3 m/s, while the calmest was 1995 at 2.1 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 15.6°C | 15.2°C | 15.8°C | 14.9°C | 15.9°C | +0.3°C |
| Avg High | 23.0°C | 21.9°C | 23.0°C | 21.3°C | 23.0°C | 0°C |
| Avg Low | 8.2°C | 8.5°C | 8.7°C | 8.5°C | 8.7°C | +0.5°C |
| Avg Rain | 6 mm | 33 mm | 15 mm | 14 mm | 12 mm | +6 mm |
May temperatures in Sunnyvale have stayed relatively stable across the record.
May has ranged from a record low of 3°C (1988) to a record high of 38°C (2001).
Rainfall in May is one of the drier months, averaging 16 mm, with a wettest year of 83 mm.
Daytime highs and overnight lows have shifted differently — highs fell about 0.2°C per decade while lows rose 0.1°C per decade, narrowing the gap between day and night.
A good time to visit Sunnyvale
May is a good time to visit Sunnyvale, with days averaging 22.4°C and nights around 8.5°C (mean 15.5°C, close to Sunnyvale's yearly average) and low rainfall. August 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 | 23.7°C | 16.4°C | 9.1°C | 35.9°C | 7.3°C | 4 mm | 70% | 2.8 m/s | 7.5 |
| 2024 | 21.6°C | 14.9°C | 8.2°C | 30.1°C | 5.2°C | 24 mm | 76% | 2.6 m/s | 7.2 |
| 2023 | 19.2°C | 13.9°C | 8.6°C | 28.1°C | 5.5°C | 22 mm | 82% | 2.4 m/s | 5.8 |
| 2022 | 23.6°C | 15.9°C | 8.2°C | 34.6°C | 3.8°C | 1 mm | 66% | 2.7 m/s | 7.5 |
| 2021 | 24.6°C | 16.6°C | 8.6°C | 36.5°C | 5.8°C | 0 mm | 65% | 3 m/s | 7.2 |
| 2020 | 25.5°C | 17.5°C | 9.6°C | 37.1°C | 5.2°C | 20 mm | 67% | 2.4 m/s | 7 |
| 2019 | 19.1°C | 13.7°C | 8.2°C | 25.7°C | 4.7°C | 65 mm | 81% | 2.5 m/s | 5.7 |
| 2018 | 21.6°C | 15.3°C | 9.1°C | 31.7°C | 6.1°C | 2 mm | 75% | 2.7 m/s | 6.5 |
| 2017 | 21.9°C | 15.4°C | 8.9°C | 31.1°C | 6.1°C | 2 mm | 77% | 2.4 m/s | 6.9 |
| 2016 | 21.9°C | 15.6°C | 9.3°C | 32.3°C | 7.3°C | 8 mm | 77% | 2.2 m/s | 6.3 |
| 2015 | 20.2°C | 14.5°C | 8.8°C | 30.0°C | 7.1°C | 11 mm | 74% | 2.7 m/s | 5.8 |
| 2014 | 24.8°C | 17.4°C | 9.9°C | 35.7°C | 6.9°C | 1 mm | 64% | 2.6 m/s | 7.3 |
| 2013 | 24.2°C | 16.7°C | 9.2°C | 32.8°C | 5.6°C | 1 mm | 65% | 2.8 m/s | 7 |
| 2012 | 22.6°C | 15.2°C | 7.7°C | 32.9°C | 5.6°C | 1 mm | 71% | 2.7 m/s | 7.2 |
| 2011 | 18.0°C | 12.5°C | 7.1°C | 26.7°C | 5.1°C | 27 mm | 78% | 2.8 m/s | 6.8 |
| 2010 | 18.4°C | 12.4°C | 6.4°C | 25.9°C | 3.6°C | 24 mm | 79% | 2.5 m/s | 6.8 |
| 2009 | 24.1°C | 16.6°C | 9.0°C | 37.5°C | 7.0°C | 20 mm | 72% | 2.5 m/s | 5.9 |
| 2008 | 23.3°C | 15.8°C | 8.3°C | 37.4°C | 3.6°C | 1 mm | 68% | 2.7 m/s | 6.7 |
| 2007 | 23.5°C | 15.9°C | 8.4°C | 33.4°C | 5.2°C | 5 mm | 66% | 2.8 m/s | 6.7 |
| 2006 | 21.3°C | 14.9°C | 8.5°C | 28.3°C | 6.6°C | 18 mm | 81% | 2.2 m/s | 7 |
| 2005 | 21.2°C | 15.0°C | 8.8°C | 29.7°C | 5.3°C | 32 mm | 81% | 2.3 m/s | 6.5 |
| 2004 | 23.2°C | 16.2°C | 9.1°C | 32.0°C | 6.4°C | 2 mm | 70% | 2.7 m/s | 7.3 |
| 2003 | 21.4°C | 14.7°C | 8.0°C | 34.1°C | 3.8°C | 25 mm | 76% | 2.3 m/s | 6.7 |
| 2002 | 21.8°C | 14.7°C | 7.7°C | 30.8°C | 5.3°C | 21 mm | 73% | 2.6 m/s | 7 |
| 2001 🔥 | 28.1°C | 19.0°C | 9.9°C | 38.0°C | 6.8°C | 1 mm | 62% | 2.4 m/s | 7.3 |
| 2000 | 22.2°C | 15.5°C | 8.9°C | 35.8°C | 3.8°C | 26 mm | 75% | 2.5 m/s | 6.9 |
| 1999 | 20.0°C | 13.3°C | 6.6°C | 27.7°C | 3.4°C | 4 mm | 76% | 2.8 m/s | 6.7 |
| 1998 ❄️ 🌧️ | 16.7°C | 12.0°C | 7.4°C | 21.4°C | 4.1°C | 83 mm | 83% | 2.3 m/s | 6.4 |
| 1997 | 27.2°C | 18.8°C | 10.3°C | 36.1°C | 4.3°C | 8 mm | 68% | 2.3 m/s | 7.3 |
| 1996 | 21.7°C | 15.3°C | 8.8°C | 29.0°C | 5.6°C | 59 mm | 75% | 2.5 m/s | 7.1 |
| 1995 | 19.0°C | 13.7°C | 8.4°C | 26.6°C | 5.8°C | 28 mm | 82% | 2.1 m/s | 6.1 |
| 1994 | 22.2°C | 15.3°C | 8.5°C | 32.6°C | 6.4°C | 36 mm | 74% | 2.3 m/s | 6.5 |
| 1993 | 21.5°C | 15.0°C | 8.6°C | 28.4°C | 4.2°C | 27 mm | 77% | 2.2 m/s | 6.6 |
| 1992 | 26.9°C | 18.5°C | 10.1°C | 32.2°C | 7.8°C | 0 mm | 70% | 2.2 m/s | 6.3 |
| 1991 | 21.5°C | 14.4°C | 7.4°C | 30.0°C | 4.3°C | 8 mm | 70% | 2.6 m/s | 6.4 |
| 1990 | 22.8°C | 15.9°C | 9.1°C | 32.5°C | 6.3°C | 73 mm | 68% | 2.7 m/s | 6.4 |
| 1989 | 22.6°C | 15.6°C | 8.6°C | 30.1°C | 5.9°C | 3 mm | 71% | 2.6 m/s | 6.7 |
| 1988 | 22.4°C | 15.1°C | 7.8°C | 34.1°C | 3.0°C | 19 mm | 67% | 2.6 m/s | 7 |
| 1987 | 25.8°C | 17.9°C | 10.1°C | 35.8°C | 5.7°C | 1 mm | 64% | 2.5 m/s | 6.6 |
| 1986 | 21.9°C | 14.7°C | 7.5°C | 30.5°C | 3.5°C | 8 mm | 75% | 2.2 m/s | 6.5 |
| 1985 | 22.6°C | 15.1°C | 7.6°C | 28.6°C | 5.0°C | 5 mm | 68% | 2.6 m/s | 6.9 |
| 1984 | 25.8°C | 17.3°C | 8.8°C | 36.5°C | 4.2°C | 1 mm | 63% | 2.7 m/s | 7.3 |
| 1983 | 19.9°C | 13.6°C | 7.3°C | 27.4°C | 3.3°C | 9 mm | 81% | 2.2 m/s | — |
| 1982 | 21.6°C | 14.7°C | 7.7°C | 29.6°C | 5.6°C | 0 mm | 79% | 2.2 m/s | — |
| 1981 | 24.0°C | 16.2°C | 8.4°C | 30.5°C | 4.2°C | 5 mm | 68% | 2.8 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 22.4°C with lows near 8.5°C (mean 15.5°C), based on 45 years of NASA POWER data.
May averages 16 mm of rainfall in Sunnyvale, one of the drier months. The wettest on record was 83 mm in 1998.
The hottest May reached 38°C in 2001. The coldest dipped to 3°C in 1988.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 0.1°C — but days and nights have moved in opposite directions. Overnight lows rose from 8°C to 8.5°C while daytime highs eased from 22.8°C to 22.5°C, narrowing the gap between day and night.
May is one of the warmer months of the year in Sunnyvale and one of the drier months, so plan for around 22.4°C daytime highs and 8.5°C at night.
Not quite — May is the 7th coolest month in Sunnyvale, averaging 15.5°C.
For May in Sunnyvale, pack light layers you can adjust through the day, with typical highs of 22.4°C and lows of 8.5°C.
Relative humidity in May averages 73% — moderately humid.
Average wind speed in May is 2.5 m/s. The windiest May on record averaged 3 m/s (2021).
The wettest May on record was 1998 with 83 mm. On average, May sees 16 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 Sunnyvale 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.
