Casper climate — normals and trends
Casper (United States) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 6.1 °C and it receives 417 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 (21.5 °C on average) and the coldest is January (-7.1 °C). Rainfall peaks in May.
Casper averages 174 frost days, 28 hot days (≥ 30 °C) and 85 rainy days per year.
Casper has warmed by +1.7 °C between 1940 and 2025, or +0.20 °C per decade. This trend is statistically significant.
The number of frost days there went from about 180 to 168 per year over the period.
The hottest day of the period reached 37.3 °C (on 24 July 2003) and the coldest -39.4 °C (on 22 December 1990).
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
CasperWyoming
- coords
- 42.87°, -106.31°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
6.1°C
Average daily high
12.1°C
Average daily low
0.1°C
Annual rainfall
417mm
Sunshine / day
10.6h
Mean relative humidity
57%
Average peak wind
20.7km/h
Seasonal range
28.6°C
Frost days (< 0 °C)
174 d/yr
Hot days (≥ 30 °C)
28 d/yr
Rainy days (≥ 1 mm)
85 d/yr
Annual snowfall
148.6 cm
Average feels-like high
8.1 °C
Average feels-like low
-3.9 °C
Average peak gust
44.4 km/h
Tropical nights (≥ 20 °C)
1 d/yr
Solar radiation
18.3 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.7 °C
since 1940
+0.2 °C per decade · r² = 0.26 · 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
37.3 °C
24 July 2003
Coldest day
-39.4 °C
22 December 1990
Wettest day
54 mm
8 May 1995
Windiest day
52.9 km/h
3 May 1964
Strongest gust
116.6 km/h
18 February 1986
Hottest feels-like
35.8 °C
13 July 2005
Coldest feels-like
-45.0 °C
22 December 1990
Snowiest day
33.4 cm
19 April 1973
Sunniest day
14.9 h
19 June 1943
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 | -4.5 °C | -2.2 °C | 20 mm | -3 mm |
| Feb | 1.7 °C | +2.3 °C | 13 mm | -11 mm |
| Mar | 7.0 °C | +3.0 °C | 49 mm | +9 mm |
| Apr | 10.8 °C | +1.0 °C | 44 mm | -18 mm |
| May | 17.0 °C | +0.7 °C | 72 mm | +4 mm |
| Jun | 26.1 °C | +2.5 °C | 29 mm | -11 mm |
| Jul | 29.9 °C | +1.1 °C | 16 mm | -5 mm |
| Aug | 27.9 °C | +0.3 °C | 27 mm | +8 mm |
| Sep | 22.6 °C | +1.2 °C | 37 mm | +7 mm |
| Oct | 14.5 °C | +1.3 °C | 37 mm | -3 mm |
| Nov | 10.4 °C | +6.0 °C | 12 mm | -16 mm |
| Dec | 6.3 °C | +7.2 °C | 21 mm | -2 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 Casper?
Casper has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 6.1 °C and it receives 417 mm of precipitation per year.
What is the hottest day ever recorded in Casper?
The hottest day measured in Casper between 1940 and 2025 was 24 July 2003, reaching 37.3 °C.
What is the coldest day in Casper?
The coldest day measured in Casper between 1940 and 2025 was 22 December 1990, at -39.4 °C.
Does it snow in Casper?
Yes. Casper gets on average 148.6 cm of snow per year and has around 174 frost days.
Has the climate of Casper warmed?
Yes: Casper warmed by +1.7 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Casper?
The wettest day measured in Casper between 1940 and 2025 was 8 May 1995, with 54 mm of rain in 24 hours.
What was the windiest day in Casper?
The windiest day measured in Casper between 1940 and 2025 was 3 May 1964, with winds reaching 52.9 km/h.
What is the warmest month in Casper?
The warmest month in Casper is July (21.5 °C on average); the coldest is January (-7.1 °C).
How much does it rain in Casper?
Casper receives on average 417 mm of precipitation per year, spread over about 85 rainy days.
Is it sunny in Casper?
Casper gets on average 10.6 hours of sunshine per day, roughly 3,869 hours per year over 1940-2025.
What is the biggest single-day snowfall in Casper?
The heaviest 24-hour snowfall measured in Casper between 1940 and 2025 was 19 April 1973, with 33.4 cm.
Are there tropical nights in Casper?
Yes: Casper has on average 1 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Casper?
In Casper, between 1940 and 2025, the highest apparent temperature reached 35.8 °C on 13 July 2005, and the lowest was -45.0 °C on 22 December 1990.
Compare Casper with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Casper