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Casper, Wyoming climate
Cfa Humid subtropical
Casper has a strongly seasonal cool-temperate climate (Humid subtropical, Köppen Cfa). The hottest month is July with an average daily high near 31°C, while the coldest is January averaging around −9°C at night. Precipitation totals about 341 mm a year and is strongly seasonal — May alone averages 70 mm while January barely receives 11 mm.
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figuresClear vs cloudy days
Share of days each month that are clear, partly cloudy or cloudy · 1991–2020 · hover a month for the day countsCasper climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 3 | 4 | 9 | 14 | 20 | 26 | 31 | 30 | 24 | 16 | 9 | 3 |
| Avg temp (°C) | −3 | −2 | 3 | 7 | 12 | 18 | 22 | 22 | 16 | 8 | 2 | −3 |
| Avg low (°C) | −9 | −8 | −4 | −1 | 5 | 10 | 14 | 13 | 7 | 1 | −4 | −8 |
| Precipitation (mm) | 11 | 16 | 25 | 37 | 70 | 39 | 31 | 26 | 27 | 32 | 11 | 17 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | 3 | 4 | 9 | 14 | 20 | 26 |
| Avg temp (°C) | −3 | −2 | 3 | 7 | 12 | 18 |
| Avg low (°C) | −9 | −8 | −4 | −1 | 5 | 10 |
| Precipitation (mm) | 11 | 16 | 25 | 37 | 70 | 39 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 31 | 30 | 24 | 16 | 9 | 3 |
| Avg temp (°C) | 22 | 22 | 16 | 8 | 2 | −3 |
| Avg low (°C) | 14 | 13 | 7 | 1 | −4 | −8 |
| Precipitation (mm) | 31 | 26 | 27 | 32 | 11 | 17 |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 5 | 5 | 5 | 7 | 9 | 7 | 6 | 6 | 6 | 5 | 4 | 5 |
| Days with high ≥ 32°C (days) | — | — | — | — | 0.3 | 5 | 16 | 11 | 2 | — | — | — |
| Days with low ≤ 0°C (days) | 27 | 25 | 24 | 17 | 4 | 0.1 | — | — | 1 | 11 | 21 | 25 |
| Days with snowfall ≥ 2.5 cm (days) | 2 | 3 | 2 | 2 | 0.4 | — | — | — | 0.1 | 1 | 1 | 3 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 5 | 5 | 5 | 7 | 9 | 7 |
| Days with high ≥ 32°C (days) | — | — | — | — | 0.3 | 5 |
| Days with low ≤ 0°C (days) | 27 | 25 | 24 | 17 | 4 | 0.1 |
| Days with snowfall ≥ 2.5 cm (days) | 2 | 3 | 2 | 2 | 0.4 | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 6 | 6 | 6 | 5 | 4 | 5 |
| Days with high ≥ 32°C (days) | 16 | 11 | 2 | — | — | — |
| Days with low ≤ 0°C (days) | — | — | 1 | 11 | 21 | 25 |
| Days with snowfall ≥ 2.5 cm (days) | — | — | 0.1 | 1 | 1 | 3 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 63 | 65 | 65 | 66 | 63 | 48 | 44 | 45 | 44 | 54 | 60 | 63 |
| Clear days (≤ 30% cloud) | 4 | 3 | 4 | 4 | 4 | 9 | 11 | 10 | 12 | 9 | 5 | 4 |
| Partly cloudy days (30–70%) | 14 | 12 | 12 | 10 | 12 | 13 | 14 | 14 | 11 | 10 | 12 | 13 |
| Cloudy days (≥ 70%) | 13 | 13 | 15 | 16 | 15 | 8 | 6 | 7 | 8 | 12 | 13 | 14 |
| Relative humidity (%) | 71 | 66 | 59 | 57 | 55 | 47 | 41 | 40 | 43 | 54 | 61 | 70 |
| Wind speed (km/h) | 17.6 | 16.1 | 14.3 | 13.0 | 11.4 | 11.0 | 9.9 | 10.2 | 11.3 | 13.0 | 15.2 | 17.1 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 63 | 65 | 65 | 66 | 63 | 48 |
| Clear days (≤ 30% cloud) | 4 | 3 | 4 | 4 | 4 | 9 |
| Partly cloudy days (30–70%) | 14 | 12 | 12 | 10 | 12 | 13 |
| Cloudy days (≥ 70%) | 13 | 13 | 15 | 16 | 15 | 8 |
| Relative humidity (%) | 71 | 66 | 59 | 57 | 55 | 47 |
| Wind speed (km/h) | 17.6 | 16.1 | 14.3 | 13.0 | 11.4 | 11.0 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 44 | 45 | 44 | 54 | 60 | 63 |
| Clear days (≤ 30% cloud) | 11 | 10 | 12 | 9 | 5 | 4 |
| Partly cloudy days (30–70%) | 14 | 14 | 11 | 10 | 12 | 13 |
| Cloudy days (≥ 70%) | 6 | 7 | 8 | 12 | 13 | 14 |
| Relative humidity (%) | 41 | 40 | 43 | 54 | 61 | 70 |
| Wind speed (km/h) | 9.9 | 10.2 | 11.3 | 13.0 | 15.2 | 17.1 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Casper Wwtp (NOAA GHCN station USC00481569), about 2 km from the city centre.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.