Casper Weather in September

What's the weather like in Casper (Wyoming) in September 2025?

The climate in Casper during September can be summarized as mild and dry.

September is in the fall / autumn in Casper and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 24°C (74°F), whilst at night 5°C (42°F) is normal.

Casper weather averages (imperial / metric)
Daytime temperature	23.6°C 74.4°F
Nightly temperature	5.3°C 41.5°F
Average temperature	14.4°C 57.9°F
Daily sunshine	9.4 hrs
Avg rainfall	24 mm 1 ins
Rainy days	7 days
Sea temperature	16.4°C 61.5°F
Humidity	49%
Windspeed	17.3kph 11 mph

On average September is the 6th wettest month of the year in Casper with around 24mm 1 inches of rain making it a dry time to visit. This rainfall is typically spread over 7 days, although this may vary considerably.

On the flip side this corresponds to an average of 9.4 hours of sunshine per day.

September temperatures in Casper

September rainfall

September hourly sunshine

The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Casper in September 2025.

Other monthly averages

Best places to visit in September

UV index Best time to go?

Beta

Current (hourly) weather 15 day forecast

Casper weather stats

Casper weather statistics
Hottest month:	July	30.3°C 86.5°F
Driest month:	January	13mm 0.5ins
Sunniest month:	August	10.9hrs
Coldest month:	January	0.9°C 33.6°F
Wettest month:	May	55mm 2.2ins

Map showing location of Casper (42.86663, -106.31308)