May is one of the warmer months of the year in San Tan Valley, with average highs near 32.9°C and lows around 15.7°C (mean 24.3°C). It is one of the drier months, averaging 7 mm of rainfall and 24% relative humidity across the period.
May is one of the warmer months of the year in San Tan Valley. Across 45 years of records, the warmest May in San Tan Valley was 1984 — when the month averaged 27.3°C — while the coldest was 1995 at 20.6°C. Typical May days reach 32.9°C with nights near 15.7°C. The long-term trend is warming, about 0.3°C per decade.
May is one of the drier months in San Tan Valley, averaging 7 mm of rainfall. The wettest May on record was 1992 with 59 mm, while the driest were 2014, 2021 and 2024, among others at 0 mm.
Relative humidity in San Tan Valley during May averages 24%. The most humid May was 1992 at 47%, and the least humid was 2002 at 14%.
May receives about 8 kWh/m²/day of solar energy in San Tan Valley. The sunniest Mays were 2012 and 2022 at 8.6 kWh/m²/day, and the cloudiest was 1992 at 6.7.
Average wind speed in San Tan Valley during May is 2.4 m/s. The windiest May was 1990 at 2.8 m/s, while the calmest were 2005, 2009 and 2024, among others at 2.1 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 23.9°C | 23.4°C | 25.4°C | 23.9°C | 25.5°C | +1.6°C |
| Avg High | 32.7°C | 31.9°C | 34.1°C | 32.3°C | 34.2°C | +1.5°C |
| Avg Low | 15.1°C | 14.9°C | 16.6°C | 15.4°C | 16.8°C | +1.7°C |
| Avg Rain | 8 mm | 12 mm | 7 mm | 4 mm | 1 mm | -7 mm |
May temperatures in San Tan Valley have risen by about 1.3°C between 1981–1985 and 2021–2025.
May has ranged from a record low of 4.1°C (1988) to a record high of 43.7°C (2020).
Rainfall in May is one of the drier months, averaging 7 mm, with a wettest year of 59 mm.
One of the best times to visit San Tan Valley
May is one of the best times to visit San Tan Valley. Expect days averaging 32.9°C and nights around 15.7°C (mean 24.3°C) — warmer than San Tan Valley's yearly average — with low rainfall (7 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 33.4°C | 24.9°C | 16.4°C | 39.5°C | 9.7°C | 3 mm | 19% | 2.4 m/s | 7.8 |
| 2024 | 33.3°C | 24.8°C | 16.2°C | 39.2°C | 10.9°C | 0 mm | 21% | 2.1 m/s | 8.3 |
| 2023 | 33.2°C | 25.1°C | 17.1°C | 37.2°C | 10.1°C | 4 mm | 25% | 2.4 m/s | 8.2 |
| 2022 | 35.1°C | 25.7°C | 16.4°C | 39.7°C | 10.7°C | 0 mm | 15% | 2.5 m/s | 8.6 |
| 2021 | 34.3°C | 25.4°C | 16.5°C | 37.7°C | 11.9°C | 0 mm | 14% | 2.4 m/s | 8.5 |
| 2020 | 35.8°C | 26.8°C | 17.9°C | 43.7°C | 12.5°C | 1 mm | 21% | 2.4 m/s | 8.5 |
| 2019 | 28.9°C | 21.6°C | 14.3°C | 36.3°C | 9.4°C | 6 mm | 30% | 2.3 m/s | 7.5 |
| 2018 | 34.4°C | 26.0°C | 17.6°C | 40.0°C | 10.3°C | 1 mm | 17% | 2.4 m/s | 8.3 |
| 2017 | 33.2°C | 24.6°C | 15.9°C | 40.9°C | 10.7°C | 3 mm | 21% | 2.5 m/s | 8.1 |
| 2016 | 32.0°C | 23.9°C | 15.8°C | 38.5°C | 11.2°C | 3 mm | 24% | 2.5 m/s | 8.2 |
| 2015 | 29.9°C | 22.4°C | 14.9°C | 39.7°C | 9.7°C | 26 mm | 32% | 2.3 m/s | 7.7 |
| 2014 | 33.5°C | 24.8°C | 16.1°C | 39.9°C | 9.4°C | 0 mm | 18% | 2.7 m/s | 8.1 |
| 2013 | 33.8°C | 25.2°C | 16.5°C | 37.3°C | 12.2°C | 1 mm | 19% | 2.7 m/s | 8.2 |
| 2012 | 35.1°C | 25.9°C | 16.6°C | 41.0°C | 12.4°C | 1 mm | 15% | 2.7 m/s | 8.6 |
| 2011 | 31.4°C | 22.5°C | 13.5°C | 37.2°C | 6.9°C | 2 mm | 18% | 2.7 m/s | 8.4 |
| 2010 | 31.1°C | 22.1°C | 13.0°C | 37.5°C | 6.5°C | 0 mm | 25% | 2.4 m/s | 8.5 |
| 2009 | 34.7°C | 26.6°C | 18.5°C | 40.0°C | 14.6°C | 12 mm | 25% | 2.1 m/s | 7.6 |
| 2008 | 30.6°C | 22.3°C | 14.0°C | 40.1°C | 8.7°C | 24 mm | 26% | 2.6 m/s | 7.8 |
| 2007 | 34.2°C | 25.7°C | 17.1°C | 40.6°C | 9.1°C | 6 mm | 22% | 2.3 m/s | 8.2 |
| 2006 | 34.7°C | 26.1°C | 17.5°C | 38.9°C | 13.0°C | 1 mm | 17% | 2.3 m/s | 8.3 |
| 2005 | 32.7°C | 24.4°C | 16.1°C | 41.7°C | 9.9°C | 8 mm | 30% | 2.1 m/s | 8.2 |
| 2004 | 34.5°C | 25.4°C | 16.3°C | 37.8°C | 10.8°C | 0 mm | 17% | 2.6 m/s | 8.4 |
| 2003 | 33.8°C | 25.1°C | 16.3°C | 41.6°C | 9.3°C | 4 mm | 21% | 2.3 m/s | 8 |
| 2002 | 33.9°C | 24.7°C | 15.6°C | 41.8°C | 9.6°C | 0 mm | 14% | 2.4 m/s | 8.4 |
| 2001 | 35.6°C | 26.5°C | 17.5°C | 41.0°C | 8.1°C | 8 mm | 24% | 2.3 m/s | 8.2 |
| 2000 | 36.1°C | 26.8°C | 17.5°C | 42.8°C | 9.9°C | 0 mm | 16% | 2.5 m/s | 8.5 |
| 1999 | 32.5°C | 23.6°C | 14.8°C | 39.6°C | 7.2°C | 0 mm | 20% | 2.6 m/s | 8.2 |
| 1998 | 29.8°C | 21.4°C | 13.0°C | 35.9°C | 7.8°C | 1 mm | 36% | 2.3 m/s | 8 |
| 1997 | 35.8°C | 27.2°C | 18.5°C | 41.0°C | 11.6°C | 9 mm | 22% | 2.4 m/s | 8 |
| 1996 | 35.1°C | 25.7°C | 16.2°C | 42.2°C | 12.3°C | 0 mm | 17% | 2.6 m/s | 8.3 |
| 1995 ❄️ | 28.6°C | 20.6°C | 12.6°C | 35.5°C | 7.1°C | 6 mm | 35% | 2.4 m/s | 7.6 |
| 1994 | 31.7°C | 23.3°C | 14.9°C | 38.2°C | 9.5°C | 20 mm | 28% | 2.1 m/s | 7.5 |
| 1993 | 32.3°C | 23.8°C | 15.4°C | 37.1°C | 9.8°C | 14 mm | 38% | 2.3 m/s | 8.1 |
| 1992 🌧️ | 31.3°C | 24.0°C | 16.6°C | 36.6°C | 12.6°C | 59 mm | 47% | 2.2 m/s | 6.7 |
| 1991 | 30.8°C | 21.8°C | 12.8°C | 36.6°C | 6.8°C | 2 mm | 27% | 2.7 m/s | 8 |
| 1990 | 31.5°C | 22.8°C | 14.1°C | 38.3°C | 8.9°C | 5 mm | 23% | 2.8 m/s | 7.8 |
| 1989 | 33.8°C | 24.9°C | 15.9°C | 41.1°C | 10.4°C | 4 mm | 20% | 2.6 m/s | 7.8 |
| 1988 | 32.2°C | 23.4°C | 14.6°C | 38.4°C | 4.1°C | 0 mm | 25% | 2.5 m/s | 7.4 |
| 1987 | 30.9°C | 23.2°C | 15.4°C | 34.5°C | 9.6°C | 15 mm | 32% | 2.4 m/s | 7.4 |
| 1986 | 33.5°C | 24.4°C | 15.3°C | 39.4°C | 8.1°C | 4 mm | 22% | 2.5 m/s | 8 |
| 1985 | 33.2°C | 24.6°C | 16.1°C | 38.2°C | 9.9°C | 1 mm | 27% | 2.6 m/s | 7.6 |
| 1984 🔥 | 36.6°C | 27.3°C | 17.9°C | 42.8°C | 9.2°C | 6 mm | 22% | 2.5 m/s | 7.6 |
| 1983 | 31.4°C | 22.2°C | 12.9°C | 40.8°C | 7.2°C | 1 mm | 33% | 2.5 m/s | — |
| 1982 | 31.1°C | 22.4°C | 13.7°C | 37.5°C | 7.1°C | 27 mm | 31% | 2.4 m/s | — |
| 1981 | 31.4°C | 22.9°C | 14.3°C | 35.4°C | 10.8°C | 15 mm | 27% | 2.5 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 32.9°C with lows near 15.7°C (mean 24.3°C), based on 45 years of NASA POWER data.
May averages 7 mm of rainfall in San Tan Valley, one of the drier months. The wettest on record was 59 mm in 1992.
The hottest May reached 43.7°C in 2020. The coldest dipped to 4.1°C in 1988.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 1.3°C. Daytime highs moved from 32.7°C to 33.9°C and overnight lows from 15°C to 16.5°C over the same span.
May is one of the warmer months of the year in San Tan Valley and one of the drier months, so plan for around 32.9°C daytime highs and 15.7°C at night.
Not quite — May is the 8th coolest month in San Tan Valley, averaging 24.3°C.
For May in San Tan Valley, pack light, breathable clothing and sun protection, with typical highs of 32.9°C and lows of 15.7°C.
Relative humidity in May averages 24% — relatively dry.
Average wind speed in May is 2.4 m/s. The windiest May on record averaged 2.8 m/s (1990).
The wettest May on record was 1992 with 59 mm. On average, May sees 7 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 Tan Valley 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.
