May is one of the warmer months of the year in Decatur, with average highs near 26.7°C and lows around 14.5°C (mean 20.6°C). It is one of the drier months, averaging 90 mm of rainfall and 75% 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 2004 — when the month averaged 23.3°C — while the coldest was 1997 at 18°C. Typical May days reach 26.7°C with nights near 14.5°C. The long-term trend is warming, about 0.3°C per decade.
May is one of the drier months in Decatur, averaging 90 mm of rainfall. The wettest May on record was 2003 with 235 mm, while the driest was 2007 at 26 mm.
Relative humidity in Decatur during May averages 75%. The most humid May was 2009 at 86%, and the least humid was 2007 at 57%.
May receives about 6 kWh/m²/day of solar energy in Decatur. The sunniest Mays were 2007 and 2019 at 6.8 kWh/m²/day, and the cloudiest were 1991 and 2009 at 4.8.
Average wind speed in Decatur during May is 1.2 m/s. The windiest Mays were 2006, 2008 and 2009, among others at 1.4 m/s, while the calmest were 1982 and 1987 at 0.9 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 19.8°C | 20.2°C | 21.1°C | 21.2°C | 20.7°C | +0.9°C |
| Avg High | 26.2°C | 26.2°C | 27.4°C | 27.2°C | 26.4°C | +0.2°C |
| Avg Low | 13.5°C | 14.3°C | 14.7°C | 15.3°C | 14.9°C | +1.4°C |
| Avg Rain | 89 mm | 82 mm | 88 mm | 99 mm | 94 mm | +4 mm |
May temperatures in Decatur have risen by about 1.5°C between 1981–1985 and 2021–2025.
May has ranged from a record low of 3.5°C (2011) to a record high of 35.7°C (2006).
Rainfall in May is one of the drier months, averaging 90 mm, with a wettest year of 235 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.2°C per decade while lows rose 0.4°C per decade, narrowing the gap between day and night.
One of the best times to visit Decatur
May is one of the best times to visit Decatur. Expect days averaging 26.7°C and nights around 14.5°C (mean 20.6°C) — warmer than Decatur's yearly average — with higher rainfall (90 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 | 26.7°C | 21.4°C | 16.1°C | 31.5°C | 10.1°C | 186 mm | 79% | 1.2 m/s | 5.3 |
| 2024 | 27.4°C | 22.1°C | 16.8°C | 30.9°C | 11.0°C | 93 mm | 79% | 1.1 m/s | 5.8 |
| 2023 | 24.9°C | 19.6°C | 14.2°C | 30.9°C | 5.4°C | 60 mm | 81% | 1.3 m/s | 5.6 |
| 2022 | 28.8°C | 22.2°C | 15.6°C | 34.5°C | 9.2°C | 57 mm | 71% | 1.2 m/s | 6.2 |
| 2021 | 26.1°C | 19.8°C | 13.4°C | 33.0°C | 6.4°C | 101 mm | 73% | 1.3 m/s | 6.4 |
| 2020 | 24.7°C | 19.0°C | 13.3°C | 29.7°C | 4.7°C | 64 mm | 80% | 1.2 m/s | 6.4 |
| 2019 | 28.8°C | 22.9°C | 16.9°C | 33.8°C | 8.7°C | 56 mm | 76% | 1.1 m/s | 6.8 |
| 2018 | 27.4°C | 22.1°C | 16.8°C | 31.5°C | 8.4°C | 148 mm | 80% | 1.1 m/s | 5.9 |
| 2017 | 27.1°C | 20.9°C | 14.7°C | 33.1°C | 6.6°C | 148 mm | 74% | 1.3 m/s | 6.2 |
| 2016 | 26.1°C | 20.1°C | 14.1°C | 33.0°C | 5.7°C | 54 mm | 76% | 1.2 m/s | 6.5 |
| 2015 | 27.0°C | 21.2°C | 15.5°C | 29.8°C | 7.6°C | 101 mm | 78% | 1 m/s | 6.6 |
| 2014 | 26.0°C | 20.3°C | 14.7°C | 30.1°C | 7.0°C | 87 mm | 81% | 1.1 m/s | 6.3 |
| 2013 | 24.3°C | 18.8°C | 13.4°C | 28.8°C | 4.8°C | 128 mm | 81% | 1.3 m/s | 5.9 |
| 2012 | 29.3°C | 22.9°C | 16.6°C | 35.7°C | 10.0°C | 83 mm | 70% | 1.1 m/s | 6.3 |
| 2011 | 28.5°C | 21.3°C | 14.0°C | 35.1°C | 3.5°C | 38 mm | 68% | 1.2 m/s | 6.7 |
| 2010 | 27.0°C | 21.7°C | 16.4°C | 30.2°C | 8.4°C | 144 mm | 82% | 1.2 m/s | 5.9 |
| 2009 | 24.7°C | 20.4°C | 16.0°C | 29.9°C | 6.0°C | 128 mm | 86% | 1.4 m/s | 4.8 |
| 2008 | 26.9°C | 20.4°C | 13.8°C | 33.4°C | 8.2°C | 81 mm | 74% | 1.4 m/s | 6.2 |
| 2007 | 29.7°C | 22.0°C | 14.3°C | 32.7°C | 7.7°C | 26 mm | 57% | 1.2 m/s | 6.8 |
| 2006 | 28.0°C | 21.3°C | 14.6°C | 35.7°C | 7.8°C | 51 mm | 69% | 1.4 m/s | 6.3 |
| 2005 | 24.6°C | 18.6°C | 12.5°C | 29.0°C | 5.4°C | 67 mm | 78% | 1.2 m/s | 6.2 |
| 2004 🔥 | 30.0°C | 23.3°C | 16.5°C | 34.0°C | 4.5°C | 83 mm | 68% | 1.2 m/s | 5.9 |
| 2003 🌧️ | 25.6°C | 20.7°C | 15.8°C | 29.1°C | 9.3°C | 235 mm | 85% | 1.3 m/s | 4.9 |
| 2002 | 27.9°C | 20.8°C | 13.8°C | 31.5°C | 5.4°C | 77 mm | 68% | 1.3 m/s | 6.2 |
| 2001 | 26.0°C | 20.0°C | 14.1°C | 30.1°C | 8.4°C | 92 mm | 77% | 1.2 m/s | 6.2 |
| 2000 | 30.7°C | 23.2°C | 15.7°C | 35.1°C | 8.9°C | 36 mm | 62% | 1.3 m/s | 6.3 |
| 1999 | 28.2°C | 21.0°C | 13.7°C | 31.3°C | 5.4°C | 74 mm | 66% | 1.3 m/s | 6.3 |
| 1998 | 27.7°C | 22.1°C | 16.4°C | 31.1°C | 8.9°C | 73 mm | 79% | 1.1 m/s | 6.7 |
| 1997 ❄️ | 24.1°C | 18.0°C | 12.0°C | 29.0°C | 5.5°C | 103 mm | 78% | 1.4 m/s | 5.9 |
| 1996 | 27.1°C | 21.3°C | 15.6°C | 31.3°C | 5.7°C | 61 mm | 80% | 1.1 m/s | 6.6 |
| 1995 | 27.6°C | 21.4°C | 15.3°C | 32.9°C | 6.8°C | 65 mm | 73% | 1.2 m/s | 6.1 |
| 1994 | 25.0°C | 18.8°C | 12.6°C | 29.1°C | 8.4°C | 55 mm | 77% | 1.3 m/s | 6.5 |
| 1993 | 24.7°C | 19.3°C | 13.9°C | 28.8°C | 6.5°C | 92 mm | 80% | 1.2 m/s | 5.8 |
| 1992 | 25.1°C | 18.9°C | 12.7°C | 29.9°C | 5.2°C | 40 mm | 74% | 1.3 m/s | 5.8 |
| 1991 | 26.8°C | 22.1°C | 17.4°C | 31.2°C | 9.3°C | 164 mm | 84% | 1.2 m/s | 4.8 |
| 1990 | 25.2°C | 19.3°C | 13.4°C | 29.4°C | 6.9°C | 96 mm | 78% | 1.3 m/s | 6 |
| 1989 | 24.5°C | 18.3°C | 12.2°C | 32.3°C | 4.3°C | 92 mm | 78% | 1.4 m/s | 5.9 |
| 1988 | 27.0°C | 19.7°C | 12.3°C | 33.6°C | 7.2°C | 41 mm | 64% | 1.2 m/s | 6.3 |
| 1987 | 26.5°C | 21.3°C | 16.1°C | 30.0°C | 10.5°C | 73 mm | 81% | 0.9 m/s | 5.6 |
| 1986 | 28.5°C | 21.6°C | 14.7°C | 33.2°C | 6.1°C | 88 mm | 64% | 1.2 m/s | 5.6 |
| 1985 | 26.6°C | 20.3°C | 14.1°C | 34.2°C | 6.9°C | 107 mm | 72% | 1.3 m/s | 5.7 |
| 1984 | 24.9°C | 18.8°C | 12.7°C | 29.1°C | 5.3°C | 132 mm | 80% | 1.3 m/s | 5.5 |
| 1983 | 24.6°C | 18.6°C | 12.6°C | 27.7°C | 6.5°C | 74 mm | 80% | 1.4 m/s | — |
| 1982 | 26.3°C | 20.6°C | 14.9°C | 30.2°C | 6.0°C | 98 mm | 78% | 0.9 m/s | — |
| 1981 | 26.7°C | 19.3°C | 12.0°C | 32.3°C | 6.2°C | 98 mm | 66% | 1.3 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 26.7°C with lows near 14.5°C (mean 20.6°C), based on 45 years of NASA POWER data.
May averages 90 mm of rainfall in Decatur, one of the drier months. The wettest on record was 235 mm in 2003.
The hottest May reached 35.7°C in 2006. The coldest dipped to 3.5°C in 2011.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 1.5°C. Daytime highs moved from 25.8°C to 26.8°C and overnight lows from 13.3°C to 15.2°C over the same span.
May is one of the warmer months of the year in Decatur and one of the drier months, so plan for around 26.7°C daytime highs and 14.5°C at night.
Not quite — May is the 8th coolest month in Decatur, averaging 20.6°C.
For May in Decatur, pack light layers you can adjust through the day, with typical highs of 26.7°C and lows of 14.5°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 75% — quite humid.
Average wind speed in May is 1.2 m/s. The windiest May on record averaged 1.4 m/s (1983).
The wettest May on record was 2003 with 235 mm. On average, May sees 90 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.
