May is one of the warmer months of the year in Seattle, with average highs near 17.3°C and lows around 7.9°C (mean 12.6°C). It is one of the drier months, averaging 71 mm of rainfall and 80% relative humidity across the period.
May is one of the warmer months of the year in Seattle. Across 45 years of records, the warmest May in Seattle was 2023 — when the month averaged 15.2°C — while the coldest were 1999 and 2011 at 10.2°C. Typical May days reach 17.3°C with nights near 7.9°C. The long-term May temperature trend is broadly flat.
May is one of the drier months in Seattle, averaging 71 mm of rainfall. The wettest May on record was 1984 with 129 mm, while the driest was 1992 at 18 mm.
Relative humidity in Seattle during May averages 80%. The most humid May was 1998 at 85%, and the least humid was 1992 at 75%.
May receives about 5.1 kWh/m²/day of solar energy in Seattle. The sunniest May was 2023 at 6 kWh/m²/day, and the cloudiest were 1988 and 1991 at 4.3.
Average wind speed in Seattle during May is 0.6 m/s. The windiest May was 1988 at 0.8 m/s, while the calmest were 2018, 2023 and 2025 at 0.5 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 12.2°C | 12.8°C | 12.4°C | 13.0°C | 12.4°C | +0.2°C |
| Avg High | 17.0°C | 17.4°C | 17.1°C | 17.6°C | 17.1°C | +0.1°C |
| Avg Low | 7.4°C | 8.1°C | 7.7°C | 8.4°C | 7.8°C | +0.4°C |
| Avg Rain | 73 mm | 70 mm | 68 mm | 70 mm | 78 mm | +4 mm |
May temperatures in Seattle have stayed relatively stable across the record.
May has ranged from a record low of -0.4°C (2002) to a record high of 32.5°C (2005).
Rainfall in May is one of the drier months, averaging 71 mm, with a wettest year of 129 mm.
A good time to visit Seattle
May is a good time to visit Seattle, with days averaging 17.3°C and nights around 7.9°C (mean 12.6°C, warmer than Seattle's yearly average) and moderate 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 | 16.1°C | 11.4°C | 6.7°C | 24.5°C | 3.2°C | 56 mm | 83% | 0.5 m/s | 5.8 |
| 2024 | 16.3°C | 11.7°C | 7.0°C | 26.9°C | 3.9°C | 75 mm | 82% | 0.6 m/s | 5.4 |
| 2023 🔥 | 20.2°C | 15.2°C | 10.2°C | 31.3°C | 6.4°C | 49 mm | 80% | 0.5 m/s | 6 |
| 2022 | 14.8°C | 10.7°C | 6.6°C | 20.6°C | 2.8°C | 121 mm | 83% | 0.7 m/s | 4.5 |
| 2021 | 17.1°C | 12.3°C | 7.6°C | 23.5°C | 4.4°C | 48 mm | 80% | 0.7 m/s | 5.6 |
| 2020 | 18.1°C | 13.3°C | 8.6°C | 28.9°C | 4.0°C | 116 mm | 80% | 0.6 m/s | 5.2 |
| 2019 | 19.5°C | 14.4°C | 9.2°C | 28.3°C | 4.9°C | 35 mm | 78% | 0.6 m/s | 5.5 |
| 2018 | 19.3°C | 14.7°C | 10.1°C | 27.2°C | 6.4°C | 21 mm | 81% | 0.5 m/s | 5.8 |
| 2017 | 18.2°C | 13.2°C | 8.3°C | 26.6°C | 4.4°C | 72 mm | 80% | 0.6 m/s | 5.5 |
| 2016 | 18.6°C | 13.9°C | 9.3°C | 27.8°C | 6.2°C | 47 mm | 79% | 0.6 m/s | 5.4 |
| 2015 | 18.5°C | 14.0°C | 9.6°C | 25.1°C | 4.9°C | 28 mm | 81% | 0.6 m/s | 5.4 |
| 2014 | 18.3°C | 13.9°C | 9.5°C | 27.7°C | 6.0°C | 96 mm | 81% | 0.6 m/s | 5.2 |
| 2013 | 17.9°C | 13.2°C | 8.5°C | 28.6°C | 3.0°C | 86 mm | 81% | 0.6 m/s | 5.1 |
| 2012 | 16.2°C | 11.6°C | 7.0°C | 23.1°C | 2.6°C | 83 mm | 78% | 0.6 m/s | 5.4 |
| 2011 | 14.3°C | 10.2°C | 6.2°C | 20.7°C | 2.9°C | 112 mm | 82% | 0.7 m/s | 4.7 |
| 2010 | 15.1°C | 10.7°C | 6.4°C | 21.1°C | 2.4°C | 118 mm | 82% | 0.7 m/s | 4.8 |
| 2009 | 17.1°C | 12.1°C | 7.0°C | 25.3°C | 3.6°C | 100 mm | 79% | 0.7 m/s | 5.7 |
| 2008 | 17.2°C | 12.5°C | 7.7°C | 29.7°C | 3.2°C | 44 mm | 80% | 0.6 m/s | 4.6 |
| 2007 | 17.5°C | 12.4°C | 7.3°C | 27.6°C | 3.0°C | 43 mm | 78% | 0.6 m/s | 5.8 |
| 2006 | 17.7°C | 12.8°C | 8.0°C | 26.3°C | 2.8°C | 65 mm | 78% | 0.7 m/s | 5.5 |
| 2005 | 18.7°C | 14.0°C | 9.4°C | 32.5°C | 5.8°C | 108 mm | 81% | 0.7 m/s | 4.9 |
| 2004 | 17.7°C | 13.3°C | 8.9°C | 23.4°C | 5.8°C | 84 mm | 80% | 0.6 m/s | 4.6 |
| 2003 | 16.3°C | 11.9°C | 7.5°C | 24.4°C | 2.5°C | 39 mm | 79% | 0.6 m/s | 5.1 |
| 2002 | 15.8°C | 11.2°C | 6.6°C | 26.4°C | -0.4°C | 56 mm | 80% | 0.7 m/s | 4.9 |
| 2001 | 17.1°C | 12.2°C | 7.2°C | 28.3°C | 3.0°C | 52 mm | 76% | 0.6 m/s | 5.8 |
| 2000 | 15.7°C | 11.6°C | 7.5°C | 22.1°C | 3.3°C | 84 mm | 82% | 0.7 m/s | 4.9 |
| 1999 ❄️ | 14.8°C | 10.2°C | 5.7°C | 24.1°C | 2.3°C | 69 mm | 80% | 0.7 m/s | 5.3 |
| 1998 | 16.3°C | 12.4°C | 8.6°C | 26.8°C | 3.9°C | 75 mm | 85% | 0.6 m/s | 4.7 |
| 1997 | 18.9°C | 14.3°C | 9.7°C | 26.8°C | 3.5°C | 88 mm | 80% | 0.7 m/s | 5.3 |
| 1996 | 15.0°C | 10.8°C | 6.6°C | 21.5°C | 2.8°C | 112 mm | 81% | 0.6 m/s | 4.6 |
| 1995 | 19.2°C | 14.2°C | 9.2°C | 26.3°C | 3.8°C | 36 mm | 76% | 0.6 m/s | 5.6 |
| 1994 | 18.2°C | 13.5°C | 8.7°C | 23.7°C | 5.7°C | 56 mm | 79% | 0.6 m/s | 4.8 |
| 1993 | 19.4°C | 14.5°C | 9.5°C | 26.5°C | 4.5°C | 105 mm | 81% | 0.7 m/s | 4.4 |
| 1992 | 20.3°C | 14.5°C | 8.7°C | 28.7°C | 3.1°C | 18 mm | 75% | 0.6 m/s | 5.8 |
| 1991 | 15.6°C | 11.4°C | 7.2°C | 19.8°C | 3.7°C | 63 mm | 82% | 0.6 m/s | 4.3 |
| 1990 | 16.6°C | 11.9°C | 7.3°C | 23.2°C | 3.6°C | 78 mm | 81% | 0.6 m/s | 4.6 |
| 1989 | 17.2°C | 12.5°C | 7.7°C | 24.0°C | 4.3°C | 69 mm | 79% | 0.6 m/s | 4.6 |
| 1988 | 16.5°C | 11.8°C | 7.0°C | 28.2°C | 2.1°C | 102 mm | 79% | 0.8 m/s | 4.3 |
| 1987 | 18.1°C | 13.1°C | 8.1°C | 27.0°C | 3.9°C | 73 mm | 77% | 0.7 m/s | 5.3 |
| 1986 | 16.4°C | 12.1°C | 7.8°C | 27.7°C | 3.0°C | 87 mm | 81% | 0.7 m/s | 4.4 |
| 1985 | 17.1°C | 12.2°C | 7.3°C | 25.3°C | 1.7°C | 51 mm | 79% | 0.6 m/s | 5 |
| 1984 🌧️ | 14.9°C | 10.6°C | 6.3°C | 27.8°C | 3.6°C | 129 mm | 82% | 0.7 m/s | 4.9 |
| 1983 | 18.9°C | 13.8°C | 8.6°C | 31.0°C | 4.0°C | 59 mm | 78% | 0.6 m/s | — |
| 1982 | 17.0°C | 11.9°C | 6.9°C | 26.0°C | 2.6°C | 23 mm | 76% | 0.6 m/s | — |
| 1981 | 16.6°C | 11.9°C | 7.3°C | 27.7°C | 3.6°C | 66 mm | 80% | 0.6 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 17.3°C with lows near 7.9°C (mean 12.6°C), based on 45 years of NASA POWER data.
May averages 71 mm of rainfall in Seattle, one of the drier months. The wettest on record was 129 mm in 1984.
The hottest May reached 32.5°C in 2005. The coldest dipped to -0.4°C in 2002.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 0.2°C. Daytime highs moved from 16.9°C to 16.9°C and overnight lows from 7.3°C to 7.6°C over the same span.
May is one of the warmer months of the year in Seattle and one of the drier months, so plan for around 17.3°C daytime highs and 7.9°C at night.
Not quite — May is the 8th coolest month in Seattle, averaging 12.6°C.
For May in Seattle, pack warm layers and a jacket for chilly mornings, with typical highs of 17.3°C and lows of 7.9°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 80% — quite humid.
Average wind speed in May is 0.6 m/s. The windiest May on record averaged 0.8 m/s (1988).
The wettest May on record was 1984 with 129 mm. On average, May sees 71 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 Seattle 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.
