Williamsport climate — normals and trends
Williamsport (United States) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 9.4 °C and it receives 1,143 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (21.9 °C on average) and the coldest is January (-3.7 °C). Rainfall peaks in May.
Williamsport averages 120 frost days, 15 hot days (≥ 30 °C) and 130 rainy days per year.
Williamsport has warmed by +2.1 °C between 1940 and 2025, or +0.24 °C per decade. This trend is statistically significant.
The number of frost days there went from about 134 to 106 per year over the period.
The hottest day of the period reached 37.6 °C (on 22 July 2011) and the coldest -28.1 °C (on 19 January 1976).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
WilliamsportPennsylvania
- coords
- 41.24°, -77.00°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
9.4°C
Average daily high
14.2°C
Average daily low
4.7°C
Annual rainfall
1,143mm
Sunshine / day
8.5h
Mean relative humidity
72%
Average peak wind
14.4km/h
Seasonal range
25.6°C
Frost days (< 0 °C)
120 d/yr
Hot days (≥ 30 °C)
15 d/yr
Rainy days (≥ 1 mm)
130 d/yr
Annual snowfall
102.5 cm
Average feels-like high
12.6 °C
Average feels-like low
2.2 °C
Average peak gust
37.6 km/h
Tropical nights (≥ 20 °C)
10 d/yr
Solar radiation
14.1 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+2.1 °C
since 1940
+0.2 °C per decade · r² = 0.47 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
37.6 °C
22 July 2011
Coldest day
-28.1 °C
19 January 1976
Wettest day
168 mm
22 June 1972
Windiest day
48.4 km/h
25 November 1950
Strongest gust
140.4 km/h
25 November 1950
Hottest feels-like
41.3 °C
26 August 1948
Coldest feels-like
-33.4 °C
18 February 1979
Snowiest day
39.3 cm
13 March 1993
Sunniest day
14.6 h
23 June 2007
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | -0.8 °C | -1.0 °C | 23 mm | -57 mm |
| Feb | 1.9 °C | 0.0 °C | 79 mm | +1 mm |
| Mar | 12.2 °C | +5.0 °C | 83 mm | -16 mm |
| Apr | 15.8 °C | +1.5 °C | 83 mm | -20 mm |
| May | 19.1 °C | -1.0 °C | 194 mm | +79 mm |
| Jun | 25.7 °C | +1.0 °C | 146 mm | +42 mm |
| Jul | 28.5 °C | +1.3 °C | 99 mm | +5 mm |
| Aug | 25.5 °C | -0.6 °C | 51 mm | -46 mm |
| Sep | 24.4 °C | +2.3 °C | 47 mm | -53 mm |
| Oct | 16.7 °C | +0.9 °C | 144 mm | +53 mm |
| Nov | 8.9 °C | +0.2 °C | 48 mm | -48 mm |
| Dec | 1.1 °C | -1.4 °C | 74 mm | -15 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Williamsport?
Williamsport has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 9.4 °C and it receives 1,143 mm of precipitation per year.
What is the hottest day ever recorded in Williamsport?
The hottest day measured in Williamsport between 1940 and 2025 was 22 July 2011, reaching 37.6 °C.
What is the coldest day in Williamsport?
The coldest day measured in Williamsport between 1940 and 2025 was 19 January 1976, at -28.1 °C.
Does it snow in Williamsport?
Yes. Williamsport gets on average 102.5 cm of snow per year and has around 120 frost days.
Has the climate of Williamsport warmed?
Yes: Williamsport warmed by +2.1 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Williamsport?
The wettest day measured in Williamsport between 1940 and 2025 was 22 June 1972, with 168 mm of rain in 24 hours.
What was the windiest day in Williamsport?
The windiest day measured in Williamsport between 1940 and 2025 was 25 November 1950, with winds reaching 48.4 km/h.
What is the warmest month in Williamsport?
The warmest month in Williamsport is July (21.9 °C on average); the coldest is January (-3.7 °C).
How much does it rain in Williamsport?
Williamsport receives on average 1,143 mm of precipitation per year, spread over about 130 rainy days.
Is it sunny in Williamsport?
Williamsport gets on average 8.5 hours of sunshine per day, roughly 3,103 hours per year over 1940-2025.
What is the biggest single-day snowfall in Williamsport?
The heaviest 24-hour snowfall measured in Williamsport between 1940 and 2025 was 13 March 1993, with 39.3 cm.
Are there tropical nights in Williamsport?
Yes: Williamsport has on average 10 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Williamsport?
In Williamsport, between 1940 and 2025, the highest apparent temperature reached 41.3 °C on 26 August 1948, and the lowest was -33.4 °C on 18 February 1979.
Compare Williamsport with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Williamsport