Cheyenne Weather in September

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

September is in the fall / autumn in Cheyenne and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 22°C (72°F), whilst at night 6°C (43°F) is normal.

On average September is the 6th wettest month of the year in Cheyenne with around 34mm 1.3 inches of rain making it a reasonably dry time to visit. This rainfall is typically spread over 8 days, although this may vary considerably.

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

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 Cheyenne in September 2025.