May is one of the warmer months of the year in Chambersburg, with average highs near 21.3°C and lows around 9.6°C (mean 15.5°C). It is a relatively wet time of year, averaging 110 mm of rainfall and 78% relative humidity across the period.
May is one of the warmer months of the year in Chambersburg. Across 45 years of records, the warmest May in Chambersburg was 2018 — when the month averaged 18.9°C — while the coldest was 1997 at 12.6°C. Typical May days reach 21.3°C with nights near 9.6°C. The long-term trend is warming, about 0.4°C per decade.
May is a relatively wet time of year in Chambersburg, averaging 110 mm of rainfall. The wettest May on record was 2025 with 238 mm, while the driest was 2023 at 19 mm.
Relative humidity in Chambersburg during May averages 78%. The most humid May was 2003 at 85%, and the least humid was 2023 at 68%.
May receives about 5.4 kWh/m²/day of solar energy in Chambersburg. The sunniest May was 2007 at 6.5 kWh/m²/day, and the cloudiest was 2003 at 3.8.
Average wind speed in Chambersburg during May is 1 m/s. The windiest May was 1997 at 1.2 m/s, while the calmest were 2012, 2023 and 2024 at 0.8 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 14.8°C | 14.7°C | 15.3°C | 16.8°C | 15.6°C | +0.8°C |
| Avg High | 20.7°C | 20.7°C | 21.2°C | 22.3°C | 21.3°C | +0.6°C |
| Avg Low | 8.9°C | 8.8°C | 9.3°C | 11.2°C | 9.8°C | +0.9°C |
| Avg Rain | 119 mm | 91 mm | 104 mm | 125 mm | 114 mm | -6 mm |
May temperatures in Chambersburg have risen by about 1.4°C between 1981–1985 and 2021–2025.
May has ranged from a record low of -2.8°C (2020) to a record high of 33°C (2006).
Rainfall in May is a relatively wet time of year, averaging 110 mm, with a wettest year of 238 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 Chambersburg
May is a good time to visit Chambersburg, with days averaging 21.3°C and nights around 9.6°C (mean 15.5°C, warmer than Chambersburg's yearly average) and higher rainfall. August and June 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 🌧️ | 21.3°C | 16.0°C | 10.7°C | 28.1°C | 4.4°C | 238 mm | 79% | 1 m/s | 5 |
| 2024 | 22.5°C | 17.5°C | 12.5°C | 28.1°C | 6.6°C | 121 mm | 82% | 0.8 m/s | 5 |
| 2023 | 21.6°C | 14.9°C | 8.2°C | 28.3°C | 1.7°C | 19 mm | 68% | 0.8 m/s | 6.3 |
| 2022 | 22.2°C | 16.4°C | 10.5°C | 31.4°C | 1.6°C | 164 mm | 79% | 1 m/s | 5.2 |
| 2021 | 21.2°C | 15.0°C | 8.9°C | 29.8°C | 1.4°C | 92 mm | 74% | 0.9 m/s | 5.6 |
| 2020 | 19.1°C | 13.6°C | 8.0°C | 26.6°C | -2.8°C | 47 mm | 78% | 1.1 m/s | 5.3 |
| 2019 | 22.4°C | 17.3°C | 12.2°C | 27.5°C | 4.4°C | 168 mm | 83% | 1 m/s | 5.1 |
| 2018 🔥 | 24.4°C | 18.9°C | 13.3°C | 29.2°C | 3.2°C | 153 mm | 84% | 0.9 m/s | 5 |
| 2017 | 20.3°C | 14.9°C | 9.4°C | 29.7°C | 0.3°C | 154 mm | 79% | 1.1 m/s | 4.9 |
| 2016 | 20.0°C | 14.9°C | 9.8°C | 29.9°C | 0.5°C | 114 mm | 80% | 0.9 m/s | 4.8 |
| 2015 | 25.0°C | 18.6°C | 12.3°C | 30.6°C | 2.8°C | 60 mm | 73% | 0.9 m/s | 6.2 |
| 2014 | 21.4°C | 15.7°C | 9.9°C | 28.9°C | 2.7°C | 117 mm | 79% | 0.9 m/s | 5.6 |
| 2013 | 21.4°C | 15.4°C | 9.4°C | 30.9°C | -0.4°C | 80 mm | 78% | 1 m/s | 5.7 |
| 2012 | 23.8°C | 18.6°C | 13.3°C | 29.4°C | 4.1°C | 163 mm | 81% | 0.8 m/s | 5.6 |
| 2011 | 22.1°C | 17.0°C | 11.8°C | 32.3°C | 2.0°C | 136 mm | 84% | 0.9 m/s | 5.4 |
| 2010 | 22.4°C | 16.7°C | 11.0°C | 30.3°C | -0.4°C | 106 mm | 79% | 1 m/s | 5.4 |
| 2009 | 21.0°C | 15.6°C | 10.1°C | 28.8°C | 3.4°C | 155 mm | 80% | 1 m/s | 5.2 |
| 2008 | 19.3°C | 13.5°C | 7.7°C | 26.8°C | 2.8°C | 150 mm | 79% | 1.1 m/s | 5.4 |
| 2007 | 23.4°C | 16.6°C | 9.8°C | 32.4°C | 3.4°C | 46 mm | 72% | 0.9 m/s | 6.5 |
| 2006 | 21.3°C | 15.2°C | 9.0°C | 33.0°C | 2.2°C | 70 mm | 72% | 0.9 m/s | 5.8 |
| 2005 | 19.0°C | 12.9°C | 6.7°C | 27.1°C | 0.1°C | 42 mm | 76% | 1 m/s | 5.5 |
| 2004 | 24.1°C | 18.5°C | 12.9°C | 28.2°C | 1.9°C | 128 mm | 82% | 0.9 m/s | 5.7 |
| 2003 | 18.1°C | 13.6°C | 9.1°C | 24.5°C | 4.4°C | 174 mm | 85% | 0.9 m/s | 3.8 |
| 2002 | 21.2°C | 14.6°C | 8.1°C | 29.5°C | 0.1°C | 110 mm | 73% | 1.1 m/s | 5.9 |
| 2001 | 22.4°C | 15.9°C | 9.5°C | 30.5°C | 3.2°C | 68 mm | 69% | 1 m/s | 5.7 |
| 2000 | 22.6°C | 16.5°C | 10.4°C | 29.3°C | 2.2°C | 102 mm | 77% | 0.9 m/s | 5.3 |
| 1999 | 22.7°C | 16.0°C | 9.3°C | 31.7°C | 4.2°C | 49 mm | 70% | 1 m/s | 6.2 |
| 1998 | 22.0°C | 16.9°C | 11.7°C | 29.1°C | 6.7°C | 131 mm | 82% | 0.9 m/s | 5.5 |
| 1997 ❄️ | 19.0°C | 12.6°C | 6.2°C | 28.5°C | 0.1°C | 83 mm | 71% | 1.2 m/s | 6 |
| 1996 | 18.9°C | 13.4°C | 8.0°C | 29.1°C | -1.0°C | 120 mm | 81% | 1 m/s | 4.8 |
| 1995 | 20.7°C | 14.7°C | 8.7°C | 28.7°C | 1.6°C | 85 mm | 75% | 1 m/s | 5.2 |
| 1994 | 18.9°C | 12.7°C | 6.5°C | 27.7°C | 1.2°C | 78 mm | 77% | 1.1 m/s | 5.7 |
| 1993 | 21.3°C | 15.4°C | 9.6°C | 27.1°C | 3.6°C | 57 mm | 79% | 0.9 m/s | 5.7 |
| 1992 | 19.6°C | 13.6°C | 7.6°C | 29.3°C | 1.4°C | 91 mm | 76% | 0.9 m/s | 5.4 |
| 1991 | 24.0°C | 18.2°C | 12.3°C | 31.7°C | 4.4°C | 58 mm | 78% | 0.9 m/s | 6.1 |
| 1990 | 19.6°C | 13.9°C | 8.1°C | 25.0°C | 3.2°C | 156 mm | 77% | 1.1 m/s | 4.9 |
| 1989 | 18.9°C | 13.9°C | 8.8°C | 27.5°C | 2.8°C | 197 mm | 82% | 1.1 m/s | 4.6 |
| 1988 | 20.9°C | 15.3°C | 9.7°C | 28.5°C | 1.9°C | 180 mm | 80% | 0.9 m/s | 5.3 |
| 1987 | 21.5°C | 15.4°C | 9.2°C | 29.9°C | 0.3°C | 90 mm | 81% | 0.9 m/s | 5.5 |
| 1986 | 21.7°C | 15.6°C | 9.5°C | 28.8°C | -1.4°C | 65 mm | 77% | 0.9 m/s | 6.1 |
| 1985 | 21.7°C | 15.5°C | 9.4°C | 27.3°C | 0.1°C | 148 mm | 78% | 1 m/s | 5.6 |
| 1984 | 18.8°C | 13.2°C | 7.6°C | 25.6°C | 0.9°C | 111 mm | 81% | 1.1 m/s | 4.4 |
| 1983 | 19.2°C | 13.3°C | 7.4°C | 24.3°C | -2.0°C | 131 mm | 80% | 1 m/s | — |
| 1982 | 22.8°C | 16.7°C | 10.5°C | 28.1°C | 3.3°C | 69 mm | 78% | 0.9 m/s | — |
| 1981 | 21.0°C | 14.3°C | 7.7°C | 29.4°C | -0.4°C | 85 mm | 73% | 1 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 21.3°C with lows near 9.6°C (mean 15.5°C), based on 45 years of NASA POWER data.
May averages 110 mm of rainfall in Chambersburg, a relatively wet time of year. The wettest on record was 238 mm in 2025.
The hottest May reached 33°C in 2006. The coldest dipped to -2.8°C in 2020.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 1.4°C. Daytime highs moved from 20.7°C to 21.8°C and overnight lows from 8.5°C to 10.2°C over the same span.
May is one of the warmer months of the year in Chambersburg and a relatively wet time of year, so plan for around 21.3°C daytime highs and 9.6°C at night.
Not quite — May is the 8th coolest month in Chambersburg, averaging 15.5°C.
For May in Chambersburg, pack light layers you can adjust through the day, with typical highs of 21.3°C and lows of 9.6°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 78% — quite humid.
Average wind speed in May is 1 m/s. The windiest May on record averaged 1.2 m/s (1997).
The wettest May on record was 2025 with 238 mm. On average, May sees 110 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 Chambersburg 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.
