September in Casper averages a daily high of 25°C with nights around 7.3°C. Expect roughly 5.9 wet days totalling 27.7mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Casper is June.
Based on CASPER WASTE WATER TREATMENT PLANT, WY US (1.8km), 1995–2024. 23 years of September data.