May is one of the warmer months of the year in San Antonio, with average highs near 31.7°C and lows around 18.9°C (mean 25.3°C). It is a relatively wet time of year, averaging 104 mm of rainfall and 68% relative humidity across the period.
May is one of the warmer months of the year in San Antonio. Across 45 years of records, the warmest May in San Antonio was 2024 — when the month averaged 29.1°C — while the coldest was 1992 at 21.4°C. Typical May days reach 31.7°C with nights near 18.9°C. The long-term trend is warming, about 0.3°C per decade.
May is a relatively wet time of year in San Antonio, averaging 104 mm of rainfall. The wettest May on record was 2015 with 281 mm, while the driest was 2003 at 11 mm.
Relative humidity in San Antonio during May averages 68%. The most humid May was 2015 at 86%, and the least humid was 1998 at 53%.
May receives about 5.8 kWh/m²/day of solar energy in San Antonio. The sunniest Mays were 2006 and 2018 at 6.7 kWh/m²/day, and the cloudiest was 2015 at 4.6.
Average wind speed in San Antonio during May is 3.1 m/s. The windiest May was 1996 at 4.1 m/s, while the calmest was 2023 at 2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 24.8°C | 24.9°C | 25.8°C | 25.0°C | 26.4°C | +1.6°C |
| Avg High | 31.5°C | 31.3°C | 32.2°C | 31.2°C | 32.7°C | +1.2°C |
| Avg Low | 18.1°C | 18.6°C | 19.3°C | 18.9°C | 20.2°C | +2.1°C |
| Avg Rain | 108 mm | 113 mm | 68 mm | 125 mm | 107 mm | -1 mm |
May temperatures in San Antonio have risen by about 2°C between 1981–1985 and 2021–2025.
May has ranged from a record low of 6°C (2013) to a record high of 42.7°C (1984).
Rainfall in May is a relatively wet time of year, averaging 104 mm, with a wettest year of 281 mm.
One of the best times to visit San Antonio
May is one of the best times to visit San Antonio. Expect days averaging 31.7°C and nights around 18.9°C (mean 25.3°C) — warmer than San Antonio's yearly average — with higher rainfall (104 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 | 34.2°C | 27.3°C | 20.4°C | 40.8°C | 14.6°C | 112 mm | 63% | 3 m/s | 6.1 |
| 2024 🔥 | 35.9°C | 29.1°C | 22.4°C | 42.5°C | 17.5°C | 49 mm | 66% | 3 m/s | 4.9 |
| 2023 | 29.3°C | 24.2°C | 19.1°C | 36.1°C | 12.5°C | 124 mm | 79% | 2 m/s | 5.3 |
| 2022 | 36.2°C | 28.9°C | 21.6°C | 39.6°C | 15.4°C | 36 mm | 61% | 3.6 m/s | 6.4 |
| 2021 | 29.0°C | 23.9°C | 18.8°C | 34.1°C | 13.6°C | 167 mm | 79% | 3.1 m/s | 5.3 |
| 2020 | 31.4°C | 25.1°C | 18.9°C | 37.0°C | 13.8°C | 154 mm | 69% | 3 m/s | 6.4 |
| 2019 | 30.8°C | 25.3°C | 19.8°C | 35.5°C | 12.4°C | 93 mm | 75% | 3.4 m/s | 5.1 |
| 2018 | 34.6°C | 27.4°C | 20.2°C | 39.6°C | 14.7°C | 52 mm | 62% | 3 m/s | 6.7 |
| 2017 | 32.1°C | 25.0°C | 18.0°C | 35.9°C | 10.4°C | 69 mm | 63% | 3.2 m/s | 5.5 |
| 2016 | 29.3°C | 24.1°C | 18.9°C | 34.0°C | 11.4°C | 197 mm | 77% | 2.9 m/s | 5.1 |
| 2015 🌧️ | 27.9°C | 23.9°C | 19.9°C | 32.6°C | 10.4°C | 281 mm | 86% | 3.3 m/s | 4.6 |
| 2014 | 30.5°C | 23.9°C | 17.2°C | 36.3°C | 9.2°C | 177 mm | 65% | 3.4 m/s | 6.1 |
| 2013 | 30.1°C | 23.9°C | 17.7°C | 36.5°C | 6.0°C | 111 mm | 69% | 3.4 m/s | 5.6 |
| 2012 | 31.1°C | 25.1°C | 19.2°C | 36.4°C | 13.4°C | 145 mm | 71% | 2.8 m/s | 6.5 |
| 2011 | 34.1°C | 26.5°C | 18.9°C | 40.8°C | 7.9°C | 31 mm | 57% | 3.9 m/s | 6.1 |
| 2010 | 31.1°C | 25.1°C | 19.2°C | 36.0°C | 11.7°C | 95 mm | 70% | 3.1 m/s | 5.8 |
| 2009 | 32.1°C | 25.7°C | 19.3°C | 38.1°C | 11.7°C | 65 mm | 67% | 2.8 m/s | 6.1 |
| 2008 | 34.0°C | 26.8°C | 19.6°C | 39.2°C | 13.9°C | 33 mm | 59% | 3.3 m/s | 6.4 |
| 2007 | 28.0°C | 23.3°C | 18.7°C | 31.8°C | 14.7°C | 122 mm | 78% | 2.8 m/s | 5.2 |
| 2006 | 33.3°C | 26.3°C | 19.2°C | 37.9°C | 13.5°C | 72 mm | 62% | 3.3 m/s | 6.7 |
| 2005 | 31.1°C | 24.6°C | 18.1°C | 37.8°C | 8.7°C | 96 mm | 67% | 2.8 m/s | 5.7 |
| 2004 | 29.5°C | 23.8°C | 18.2°C | 40.2°C | 8.5°C | 61 mm | 77% | 3.3 m/s | 5.6 |
| 2003 | 35.9°C | 28.6°C | 21.2°C | 39.9°C | 18.4°C | 11 mm | 57% | 3 m/s | 5.6 |
| 2002 | 34.0°C | 26.8°C | 19.6°C | 39.3°C | 11.2°C | 46 mm | 60% | 3.8 m/s | 6 |
| 2001 | 31.5°C | 25.2°C | 18.9°C | 37.6°C | 12.3°C | 84 mm | 70% | 2.9 m/s | 6.4 |
| 2000 | 32.6°C | 26.4°C | 20.2°C | 38.4°C | 14.1°C | 90 mm | 71% | 3.4 m/s | 5.8 |
| 1999 | 32.7°C | 26.0°C | 19.3°C | 36.6°C | 12.6°C | 86 mm | 66% | 3.1 m/s | 5.9 |
| 1998 | 37.2°C | 28.6°C | 20.0°C | 41.9°C | 14.2°C | 11 mm | 53% | 3.2 m/s | 6.4 |
| 1997 | 28.1°C | 22.6°C | 17.1°C | 32.7°C | 11.5°C | 130 mm | 78% | 2.5 m/s | 5.7 |
| 1996 | 35.2°C | 28.1°C | 21.0°C | 39.8°C | 10.4°C | 38 mm | 62% | 4.1 m/s | 5.9 |
| 1995 | 32.9°C | 25.9°C | 18.9°C | 39.6°C | 12.7°C | 172 mm | 64% | 3.1 m/s | 5.5 |
| 1994 | 28.3°C | 23.3°C | 18.2°C | 34.8°C | 11.3°C | 146 mm | 80% | 2.3 m/s | 5.4 |
| 1993 | 28.6°C | 22.6°C | 16.5°C | 33.1°C | 11.7°C | 182 mm | 73% | 2.9 m/s | 6 |
| 1992 ❄️ | 26.2°C | 21.4°C | 16.6°C | 31.6°C | 8.9°C | 211 mm | 84% | 2.5 m/s | 5.4 |
| 1991 | 31.5°C | 25.5°C | 19.5°C | 37.0°C | 10.4°C | 88 mm | 73% | 2.9 m/s | 5.6 |
| 1990 | 31.8°C | 25.5°C | 19.2°C | 37.5°C | 12.4°C | 66 mm | 69% | 3.3 m/s | 5.7 |
| 1989 | 34.7°C | 27.1°C | 19.6°C | 41.0°C | 15.5°C | 56 mm | 62% | 3.5 m/s | 6.2 |
| 1988 | 32.3°C | 24.6°C | 16.9°C | 37.4°C | 11.6°C | 73 mm | 59% | 2.9 m/s | 6 |
| 1987 | 29.2°C | 24.1°C | 18.9°C | 33.8°C | 15.0°C | 225 mm | 77% | 2.5 m/s | 5.2 |
| 1986 | 30.0°C | 24.0°C | 18.0°C | 34.5°C | 11.5°C | 162 mm | 72% | 2.8 m/s | 4.7 |
| 1985 | 31.2°C | 24.6°C | 18.0°C | 38.7°C | 13.1°C | 60 mm | 69% | 2.6 m/s | 6.3 |
| 1984 | 33.7°C | 26.1°C | 18.5°C | 42.7°C | 11.0°C | 47 mm | 54% | 3.3 m/s | 6.2 |
| 1983 | 31.9°C | 24.7°C | 17.5°C | 39.4°C | 11.5°C | 105 mm | 63% | 3.2 m/s | — |
| 1982 | 29.4°C | 23.7°C | 17.9°C | 35.9°C | 9.7°C | 131 mm | 74% | 3 m/s | — |
| 1981 | 30.9°C | 24.3°C | 17.7°C | 37.8°C | 9.7°C | 115 mm | 69% | 3 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 31.7°C with lows near 18.9°C (mean 25.3°C), based on 45 years of NASA POWER data.
May averages 104 mm of rainfall in San Antonio, a relatively wet time of year. The wettest on record was 281 mm in 2015.
The hottest May reached 42.7°C in 1984. The coldest dipped to 6°C in 2013.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 2°C. Daytime highs moved from 31.4°C to 32.9°C and overnight lows from 17.9°C to 20.5°C over the same span.
May is one of the warmer months of the year in San Antonio and a relatively wet time of year, so plan for around 31.7°C daytime highs and 18.9°C at night.
Not quite — May is the 8th coolest month in San Antonio, averaging 25.3°C.
For May in San Antonio, pack light, breathable clothing and sun protection, with typical highs of 31.7°C and lows of 18.9°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 68% — moderately humid.
Average wind speed in May is 3.1 m/s. The windiest May on record averaged 4.1 m/s (1996).
The wettest May on record was 2015 with 281 mm. On average, May sees 104 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 Antonio 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.
