May is one of the warmer months of the year in Williamsport, with average highs near 19°C and lows around 7.2°C (mean 13.1°C). It is a relatively wet time of year, averaging 97 mm of rainfall and 79% relative humidity across the period.
May is one of the warmer months of the year in Williamsport. Across 45 years of records, the warmest May in Williamsport was 2012 — when the month averaged 16.3°C — while the coldest was 1997 at 9.7°C. Typical May days reach 19°C with nights near 7.2°C. The long-term trend is warming, about 0.4°C per decade.
May is a relatively wet time of year in Williamsport, averaging 97 mm of rainfall. The wettest May on record was 1989 with 195 mm, while the driest was 2023 at 16 mm.
Relative humidity in Williamsport during May averages 79%. The most humid May was 2011 at 86%, and the least humid was 2023 at 72%.
May receives about 5.3 kWh/m²/day of solar energy in Williamsport. The sunniest Mays were 2007 and 2023 at 6.6 kWh/m²/day, and the cloudiest were 1989 and 2003 at 4.1.
Average wind speed in Williamsport during May is 0 m/s. The windiest Mays were 2021, 2022 and 2023, among others at 0.1 m/s, while the calmest were 2020, 2024 and 2025, among others at 0 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 12.6°C | 12.4°C | 12.8°C | 14.4°C | 13.3°C | +0.7°C |
| Avg High | 18.5°C | 18.4°C | 18.8°C | 20.0°C | 19.1°C | +0.6°C |
| Avg Low | 6.6°C | 6.4°C | 6.9°C | 8.8°C | 7.5°C | +0.9°C |
| Avg Rain | 108 mm | 78 mm | 93 mm | 113 mm | 96 mm | -12 mm |
May temperatures in Williamsport have risen by about 1.4°C between 1981–1985 and 2021–2025.
May has ranged from a record low of -4.6°C (2020) to a record high of 33.1°C (2006).
Rainfall in May is a relatively wet time of year, averaging 97 mm, with a wettest year of 195 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 Williamsport
May is a good time to visit Williamsport, with days averaging 19°C and nights around 7.2°C (mean 13.1°C, warmer than Williamsport's yearly average) and higher rainfall. July 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 | 18.4°C | 13.2°C | 8.0°C | 25.8°C | 2.7°C | 186 mm | 84% | 0 m/s | 4.3 |
| 2024 | 20.9°C | 15.6°C | 10.3°C | 28.9°C | 3.8°C | 118 mm | 82% | 0 m/s | 5.2 |
| 2023 | 19.2°C | 12.2°C | 5.2°C | 26.8°C | -3.1°C | 16 mm | 72% | 0.1 m/s | 6.6 |
| 2022 | 20.5°C | 14.5°C | 8.5°C | 28.2°C | -0.7°C | 87 mm | 80% | 0.1 m/s | 5.4 |
| 2021 | 18.3°C | 12.6°C | 6.9°C | 27.9°C | 0.0°C | 100 mm | 77% | 0.1 m/s | 5.3 |
| 2020 | 17.0°C | 11.5°C | 6.1°C | 27.5°C | -4.6°C | 68 mm | 79% | 0 m/s | 5.6 |
| 2019 | 19.5°C | 14.1°C | 8.7°C | 25.0°C | 3.1°C | 150 mm | 83% | 0 m/s | 4.8 |
| 2018 | 21.9°C | 16.2°C | 10.4°C | 29.6°C | -0.7°C | 146 mm | 83% | 0 m/s | 5 |
| 2017 | 17.6°C | 12.3°C | 7.0°C | 27.2°C | -1.9°C | 141 mm | 81% | 0 m/s | 4.5 |
| 2016 | 18.1°C | 12.7°C | 7.4°C | 28.4°C | -0.1°C | 70 mm | 80% | 0.1 m/s | 5.1 |
| 2015 | 22.3°C | 16.0°C | 9.7°C | 27.5°C | -1.3°C | 65 mm | 76% | 0 m/s | 5.9 |
| 2014 | 19.4°C | 13.5°C | 7.6°C | 25.6°C | 0.5°C | 114 mm | 80% | 0 m/s | 5.2 |
| 2013 | 19.6°C | 13.7°C | 7.9°C | 27.8°C | -3.2°C | 83 mm | 79% | 0 m/s | 5.9 |
| 2012 🔥 | 21.8°C | 16.3°C | 10.8°C | 27.6°C | 1.9°C | 125 mm | 81% | 0.1 m/s | 5.3 |
| 2011 | 19.7°C | 14.8°C | 9.9°C | 28.5°C | 1.2°C | 158 mm | 86% | 0 m/s | 4.8 |
| 2010 | 20.5°C | 14.5°C | 8.5°C | 28.6°C | -1.7°C | 72 mm | 77% | 0 m/s | 5.5 |
| 2009 | 18.9°C | 13.0°C | 7.1°C | 26.0°C | 0.3°C | 119 mm | 78% | 0.1 m/s | 5 |
| 2008 | 17.0°C | 10.9°C | 4.7°C | 24.5°C | -3.3°C | 85 mm | 79% | 0.1 m/s | 5.2 |
| 2007 | 20.4°C | 13.5°C | 6.6°C | 27.8°C | 0.2°C | 54 mm | 75% | 0.1 m/s | 6.6 |
| 2006 | 19.0°C | 13.1°C | 7.2°C | 33.1°C | -1.2°C | 82 mm | 77% | 0.1 m/s | 5.4 |
| 2005 | 16.8°C | 10.8°C | 4.8°C | 24.7°C | -1.5°C | 33 mm | 77% | 0 m/s | 5.8 |
| 2004 | 21.4°C | 15.9°C | 10.4°C | 26.7°C | 0.4°C | 158 mm | 83% | 0 m/s | 5.3 |
| 2003 | 16.9°C | 11.9°C | 7.0°C | 22.4°C | 2.1°C | 111 mm | 84% | 0 m/s | 4.1 |
| 2002 | 17.8°C | 11.5°C | 5.3°C | 25.3°C | -2.7°C | 128 mm | 77% | 0 m/s | 5.3 |
| 2001 | 20.0°C | 13.8°C | 7.6°C | 27.3°C | 0.8°C | 55 mm | 73% | 0.1 m/s | 5.6 |
| 2000 | 19.6°C | 13.9°C | 8.1°C | 27.0°C | -0.3°C | 104 mm | 80% | 0 m/s | 5.1 |
| 1999 | 20.6°C | 14.1°C | 7.6°C | 29.7°C | 2.7°C | 46 mm | 72% | 0.1 m/s | 6.1 |
| 1998 | 20.7°C | 15.3°C | 10.0°C | 27.8°C | 3.6°C | 125 mm | 82% | 0.1 m/s | 5.5 |
| 1997 ❄️ | 15.6°C | 9.7°C | 3.7°C | 23.8°C | -2.8°C | 74 mm | 75% | 0 m/s | 5.5 |
| 1996 | 16.5°C | 10.9°C | 5.2°C | 27.1°C | -3.9°C | 86 mm | 81% | 0 m/s | 4.9 |
| 1995 | 17.4°C | 11.6°C | 5.7°C | 24.6°C | -1.4°C | 66 mm | 79% | 0 m/s | 4.8 |
| 1994 | 16.8°C | 10.5°C | 4.2°C | 25.6°C | -2.3°C | 62 mm | 78% | 0 m/s | 5.5 |
| 1993 | 19.1°C | 12.8°C | 6.5°C | 26.1°C | 0.7°C | 46 mm | 78% | 0 m/s | 5.4 |
| 1992 | 18.0°C | 11.7°C | 5.5°C | 26.1°C | -1.4°C | 94 mm | 78% | 0.1 m/s | 5 |
| 1991 | 22.1°C | 16.1°C | 10.1°C | 27.0°C | 0.8°C | 48 mm | 80% | 0 m/s | 6 |
| 1990 | 17.0°C | 11.4°C | 5.8°C | 21.7°C | -1.7°C | 136 mm | 79% | 0 m/s | 4.6 |
| 1989 🌧️ | 16.6°C | 11.6°C | 6.5°C | 25.2°C | -1.5°C | 195 mm | 84% | 0 m/s | 4.1 |
| 1988 | 19.2°C | 13.2°C | 7.2°C | 26.7°C | 0.9°C | 111 mm | 80% | 0.1 m/s | 5.4 |
| 1987 | 19.9°C | 13.4°C | 6.9°C | 27.6°C | -2.2°C | 62 mm | 79% | 0 m/s | 5.4 |
| 1986 | 19.9°C | 14.0°C | 8.1°C | 26.2°C | -3.9°C | 74 mm | 79% | 0 m/s | 6 |
| 1985 | 19.3°C | 13.2°C | 7.1°C | 25.5°C | -2.7°C | 116 mm | 78% | 0 m/s | 5.5 |
| 1984 | 16.2°C | 10.7°C | 5.2°C | 23.7°C | -1.9°C | 158 mm | 82% | 0 m/s | 4.3 |
| 1983 | 16.8°C | 10.9°C | 5.0°C | 22.1°C | -3.9°C | 98 mm | 80% | 0 m/s | — |
| 1982 | 19.7°C | 13.7°C | 7.7°C | 25.0°C | 0.3°C | 90 mm | 81% | 0.1 m/s | — |
| 1981 | 19.1°C | 12.3°C | 5.5°C | 25.4°C | -2.6°C | 64 mm | 75% | 0.1 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 19°C with lows near 7.2°C (mean 13.1°C), based on 45 years of NASA POWER data.
May averages 97 mm of rainfall in Williamsport, a relatively wet time of year. The wettest on record was 195 mm in 1989.
The hottest May reached 33.1°C in 2006. The coldest dipped to -4.6°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 18.2°C to 19.5°C and overnight lows from 6.1°C to 7.8°C over the same span.
May is one of the warmer months of the year in Williamsport and a relatively wet time of year, so plan for around 19°C daytime highs and 7.2°C at night.
Not quite — May is the 8th coolest month in Williamsport, averaging 13.1°C.
For May in Williamsport, pack warm layers and a jacket for chilly mornings, with typical highs of 19°C and lows of 7.2°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 79% — quite humid.
Average wind speed in May is 0 m/s. The windiest May on record averaged 0.1 m/s (1981).
The wettest May on record was 1989 with 195 mm. On average, May sees 97 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 Williamsport 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.
