May is one of the warmer months of the year in Decatur, with average highs near 22.7°C and lows around 11°C (mean 16.9°C). It is a relatively wet time of year, averaging 109 mm of rainfall and 76% relative humidity across the period.
May is one of the warmer months of the year in Decatur. Across 45 years of records, the warmest May in Decatur was 2018 — when the month averaged 21.4°C — while the coldest was 1983 at 13.7°C. Typical May days reach 22.7°C with nights near 11°C. The long-term trend is warming, about 0.4°C per decade.
May is a relatively wet time of year in Decatur, averaging 109 mm of rainfall. The wettest May on record was 1995 with 248 mm, while the driest was 1992 at 25 mm.
Relative humidity in Decatur during May averages 76%. The most humid May was 1991 at 84%, and the least humid was 1988 at 66%.
May receives about 5.6 kWh/m²/day of solar energy in Decatur. The sunniest Mays were 1994 and 2012 at 6.7 kWh/m²/day, and the cloudiest was 1995 at 4.7.
Average wind speed in Decatur during May is 3.2 m/s. The windiest May was 1997 at 3.8 m/s, while the calmest were 1994, 2009 and 2023, among others at 2.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 16.2°C | 16.3°C | 16.8°C | 17.9°C | 17.2°C | +1°C |
| Avg High | 22.3°C | 22.1°C | 22.7°C | 23.4°C | 23.0°C | +0.7°C |
| Avg Low | 10.0°C | 10.5°C | 10.9°C | 12.3°C | 11.4°C | +1.4°C |
| Avg Rain | 98 mm | 123 mm | 110 mm | 116 mm | 93 mm | -5 mm |
May temperatures in Decatur have risen by about 2.1°C between 1981–1985 and 2021–2025.
May has ranged from a record low of -2.7°C (1989) to a record high of 33°C (2018).
Rainfall in May is a relatively wet time of year, averaging 109 mm, with a wettest year of 248 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.3°C per decade while lows rose 0.5°C per decade, narrowing the gap between day and night.
A good time to visit Decatur
May is a good time to visit Decatur, with days averaging 22.7°C and nights around 11°C (mean 16.9°C, warmer than Decatur's yearly average) and higher rainfall. June and August 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 | 22.5°C | 16.5°C | 10.6°C | 30.0°C | 5.5°C | 76 mm | 73% | 3.1 m/s | 5.4 |
| 2024 | 25.0°C | 19.2°C | 13.5°C | 29.7°C | 9.0°C | 101 mm | 75% | 2.9 m/s | 5.9 |
| 2023 | 24.5°C | 18.1°C | 11.6°C | 31.0°C | 2.1°C | 56 mm | 68% | 2.7 m/s | 6.4 |
| 2022 | 23.6°C | 18.1°C | 12.6°C | 31.2°C | 4.4°C | 90 mm | 79% | 3.5 m/s | 5.5 |
| 2021 | 21.6°C | 15.9°C | 10.2°C | 29.0°C | 0.9°C | 110 mm | 73% | 3.1 m/s | 5.3 |
| 2020 | 20.9°C | 15.5°C | 10.1°C | 29.2°C | 0.7°C | 123 mm | 80% | 3.2 m/s | 5.3 |
| 2019 | 22.8°C | 17.6°C | 12.4°C | 29.3°C | 5.1°C | 133 mm | 81% | 3.3 m/s | 5.2 |
| 2018 🔥 | 26.9°C | 21.4°C | 16.0°C | 33.0°C | 9.0°C | 83 mm | 78% | 2.8 m/s | 5.9 |
| 2017 | 22.0°C | 16.3°C | 10.5°C | 28.9°C | 3.1°C | 140 mm | 77% | 3.5 m/s | 5.9 |
| 2016 | 21.9°C | 16.4°C | 10.9°C | 28.7°C | 2.1°C | 79 mm | 77% | 3 m/s | 5.6 |
| 2015 | 23.7°C | 18.3°C | 12.8°C | 28.4°C | 2.6°C | 129 mm | 77% | 3.4 m/s | 5.5 |
| 2014 | 23.0°C | 17.3°C | 11.7°C | 29.2°C | 2.1°C | 63 mm | 75% | 3.3 m/s | 5.9 |
| 2013 | 22.8°C | 17.6°C | 12.3°C | 28.8°C | 1.4°C | 214 mm | 81% | 3.4 m/s | 5.1 |
| 2012 | 26.0°C | 19.7°C | 13.4°C | 32.6°C | 7.2°C | 57 mm | 69% | 3.1 m/s | 6.7 |
| 2011 | 21.9°C | 16.6°C | 11.2°C | 30.3°C | 0.3°C | 118 mm | 82% | 3.3 m/s | 4.9 |
| 2010 | 22.9°C | 17.4°C | 11.8°C | 30.0°C | 1.2°C | 140 mm | 80% | 3.2 m/s | 5.4 |
| 2009 | 22.0°C | 16.3°C | 10.5°C | 27.7°C | 1.9°C | 140 mm | 77% | 2.7 m/s | 5.6 |
| 2008 | 20.3°C | 14.6°C | 8.9°C | 28.2°C | 2.3°C | 135 mm | 77% | 3.7 m/s | 5 |
| 2007 | 24.6°C | 19.1°C | 13.5°C | 29.5°C | 5.7°C | 69 mm | 76% | 3.1 m/s | 5.8 |
| 2006 | 21.8°C | 16.5°C | 11.1°C | 31.1°C | 3.9°C | 62 mm | 76% | 3.2 m/s | 5.6 |
| 2005 | 22.3°C | 15.8°C | 9.4°C | 28.4°C | -1.8°C | 46 mm | 72% | 3.2 m/s | 6.4 |
| 2004 | 24.5°C | 19.0°C | 13.5°C | 29.8°C | 0.3°C | 153 mm | 79% | 3.5 m/s | 5.4 |
| 2003 | 22.4°C | 16.2°C | 10.0°C | 30.0°C | 2.4°C | 105 mm | 73% | 3.6 m/s | 5 |
| 2002 | 20.6°C | 14.3°C | 8.0°C | 30.3°C | -0.8°C | 204 mm | 80% | 3.5 m/s | 5.5 |
| 2001 | 23.3°C | 17.7°C | 12.0°C | 30.3°C | 5.0°C | 101 mm | 74% | 3.3 m/s | 5.5 |
| 2000 | 24.7°C | 18.5°C | 12.3°C | 30.2°C | 4.0°C | 86 mm | 72% | 3.7 m/s | 5 |
| 1999 | 23.4°C | 17.3°C | 11.2°C | 27.1°C | 5.9°C | 96 mm | 76% | 3.4 m/s | 6.1 |
| 1998 | 24.7°C | 19.2°C | 13.7°C | 30.0°C | 6.9°C | 140 mm | 80% | 2.9 m/s | 5.5 |
| 1997 | 20.3°C | 14.1°C | 7.9°C | 29.0°C | 2.9°C | 83 mm | 70% | 3.8 m/s | 5.7 |
| 1996 | 22.4°C | 16.6°C | 10.9°C | 30.3°C | 3.3°C | 187 mm | 78% | 3.4 m/s | 5 |
| 1995 🌧️ | 20.9°C | 15.4°C | 9.8°C | 25.7°C | 5.1°C | 248 mm | 78% | 3.3 m/s | 4.7 |
| 1994 | 21.0°C | 14.7°C | 8.4°C | 28.4°C | 1.5°C | 65 mm | 76% | 2.7 m/s | 6.7 |
| 1993 | 21.7°C | 16.3°C | 10.8°C | 27.0°C | 3.1°C | 53 mm | 79% | 3.3 m/s | 5.4 |
| 1992 | 21.2°C | 14.9°C | 8.5°C | 27.7°C | -0.1°C | 25 mm | 72% | 3 m/s | 5.7 |
| 1991 | 24.6°C | 19.8°C | 15.0°C | 31.1°C | 3.8°C | 138 mm | 84% | 2.7 m/s | 5.2 |
| 1990 | 20.7°C | 14.9°C | 9.1°C | 26.5°C | 1.9°C | 191 mm | 77% | 3.7 m/s | 4.8 |
| 1989 | 21.0°C | 14.7°C | 8.3°C | 29.1°C | -2.7°C | 108 mm | 73% | 3.3 m/s | 5.4 |
| 1988 | 24.5°C | 17.1°C | 9.7°C | 30.6°C | 2.4°C | 39 mm | 66% | 3.1 m/s | 6.6 |
| 1987 | 25.2°C | 19.2°C | 13.2°C | 29.7°C | 3.5°C | 41 mm | 74% | 2.9 m/s | 6.6 |
| 1986 | 22.8°C | 17.1°C | 11.5°C | 27.8°C | 3.4°C | 72 mm | 76% | 3 m/s | 5.5 |
| 1985 | 22.9°C | 16.9°C | 10.9°C | 28.8°C | 3.7°C | 61 mm | 75% | 3.7 m/s | 5.7 |
| 1984 | 19.7°C | 13.8°C | 7.9°C | 26.5°C | 1.4°C | 149 mm | 78% | 3.3 m/s | 5.5 |
| 1983 ❄️ | 19.6°C | 13.7°C | 7.9°C | 24.4°C | -1.7°C | 126 mm | 79% | 3.6 m/s | — |
| 1982 | 24.9°C | 19.1°C | 13.3°C | 27.9°C | 7.5°C | 119 mm | 77% | 2.9 m/s | — |
| 1981 | 20.4°C | 14.1°C | 7.7°C | 26.8°C | 0.5°C | 168 mm | 74% | 3.4 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 22.7°C with lows near 11°C (mean 16.9°C), based on 45 years of NASA POWER data.
May averages 109 mm of rainfall in Decatur, a relatively wet time of year. The wettest on record was 248 mm in 1995.
The hottest May reached 33°C in 2018. The coldest dipped to -2.7°C in 1989.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 2.1°C. Daytime highs moved from 21.5°C to 23.4°C and overnight lows from 9.5°C to 11.7°C over the same span.
May is one of the warmer months of the year in Decatur and a relatively wet time of year, so plan for around 22.7°C daytime highs and 11°C at night.
Not quite — May is the 8th coolest month in Decatur, averaging 16.9°C.
For May in Decatur, pack light layers you can adjust through the day, with typical highs of 22.7°C and lows of 11°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 76% — quite humid.
Average wind speed in May is 3.2 m/s. The windiest May on record averaged 3.8 m/s (1997).
The wettest May on record was 1995 with 248 mm. On average, May sees 109 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 Decatur 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.
