Johnstown climate — normals and trends
Johnstown (United States) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 9.0 °C and it receives 1,228 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 (20.7 °C on average) and the coldest is January (-3.5 °C). Rainfall peaks in May.
Johnstown averages 124 frost days, 5 hot days (≥ 30 °C) and 163 rainy days per year.
Johnstown has warmed by +1.9 °C between 1940 and 2025, or +0.22 °C per decade. This trend is statistically significant.
The number of frost days there went from about 136 to 112 per year over the period.
The hottest day of the period reached 34.8 °C (on 16 July 1988) and the coldest -29.4 °C (on 19 January 1994).
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
JohnstownPennsylvania
- coords
- 40.33°, -78.92°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
9.0°C
Average daily high
13.7°C
Average daily low
4.5°C
Annual rainfall
1,228mm
Sunshine / day
8.4h
Mean relative humidity
75%
Average peak wind
17.1km/h
Seasonal range
24.2°C
Frost days (< 0 °C)
124 d/yr
Hot days (≥ 30 °C)
5 d/yr
Rainy days (≥ 1 mm)
163 d/yr
Annual snowfall
126.5 cm
Average feels-like high
11.8 °C
Average feels-like low
1.6 °C
Average peak gust
42.7 km/h
Tropical nights (≥ 20 °C)
6 d/yr
Solar radiation
14.2 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.9 °C
since 1940
+0.2 °C per decade · r² = 0.42 · 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
34.8 °C
16 July 1988
Coldest day
-29.4 °C
19 January 1994
Wettest day
110 mm
15 October 1954
Windiest day
51.5 km/h
3 April 1975
Strongest gust
119.2 km/h
25 February 1956
Hottest feels-like
40.1 °C
15 July 1995
Coldest feels-like
-37.6 °C
21 January 1985
Snowiest day
42.6 cm
13 March 1993
Sunniest day
14.7 h
4 July 2025
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 | -2.9 °C | -3.2 °C | 62 mm | -32 mm |
| Feb | 2.6 °C | +0.6 °C | 103 mm | +12 mm |
| Mar | 12.2 °C | +5.1 °C | 77 mm | -38 mm |
| Apr | 16.0 °C | +2.1 °C | 139 mm | +20 mm |
| May | 18.4 °C | -0.7 °C | 247 mm | +116 mm |
| Jun | 25.3 °C | +1.8 °C | 158 mm | +43 mm |
| Jul | 27.5 °C | +1.9 °C | 117 mm | +15 mm |
| Aug | 24.5 °C | -0.4 °C | 46 mm | -48 mm |
| Sep | 23.5 °C | +2.1 °C | 76 mm | -14 mm |
| Oct | 15.8 °C | +0.6 °C | 78 mm | -8 mm |
| Nov | 8.4 °C | 0.0 °C | 84 mm | -11 mm |
| Dec | 2.3 °C | -0.3 °C | 90 mm | -8 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 Johnstown?
Johnstown has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 9.0 °C and it receives 1,228 mm of precipitation per year.
What is the hottest day ever recorded in Johnstown?
The hottest day measured in Johnstown between 1940 and 2025 was 16 July 1988, reaching 34.8 °C.
What is the coldest day in Johnstown?
The coldest day measured in Johnstown between 1940 and 2025 was 19 January 1994, at -29.4 °C.
Does it snow in Johnstown?
Yes. Johnstown gets on average 126.5 cm of snow per year and has around 124 frost days.
Has the climate of Johnstown warmed?
Yes: Johnstown warmed by +1.9 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Johnstown?
The wettest day measured in Johnstown between 1940 and 2025 was 15 October 1954, with 110 mm of rain in 24 hours.
What was the windiest day in Johnstown?
The windiest day measured in Johnstown between 1940 and 2025 was 3 April 1975, with winds reaching 51.5 km/h.
What is the warmest month in Johnstown?
The warmest month in Johnstown is July (20.7 °C on average); the coldest is January (-3.5 °C).
How much does it rain in Johnstown?
Johnstown receives on average 1,228 mm of precipitation per year, spread over about 163 rainy days.
Is it sunny in Johnstown?
Johnstown gets on average 8.4 hours of sunshine per day, roughly 3,066 hours per year over 1940-2025.
What is the biggest single-day snowfall in Johnstown?
The heaviest 24-hour snowfall measured in Johnstown between 1940 and 2025 was 13 March 1993, with 42.6 cm.
Are there tropical nights in Johnstown?
Yes: Johnstown has on average 6 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Johnstown?
In Johnstown, between 1940 and 2025, the highest apparent temperature reached 40.1 °C on 15 July 1995, and the lowest was -37.6 °C on 21 January 1985.
Compare Johnstown with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Johnstown