Casper weather in September 2025

Expect 73°F daytime maximum temperatures in the shade with on average 9 hours of sunshine per day in Casper in September. Check more long-term weather averages for Casper in September before you book your next holiday to Wyoming in 2025/2026.

  • 73°F maximum daytime temperature in September in Casper73
    73°F max day temperature
  • 9 hours of sunshine per day
  • 7 days with some rainfall in September in Casper7
    7 days with some rainfall
  • 41°F minimum night-time temperature in September in Casper41
    41°F min night temperature
  • 12 hours of daylight per day in September in Casper12
    12 hours of daylight per day
  • No heat & humidity in September in Casper0
    No heat & humidity
  • 0.9 inches monthly rainfall in September in Casper0.9
    0.9 inches of monthly rainfall
  • UV (maximum) index 7 (High) in September in Casper7
    7 (High) UV index

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The September weather guide for Wyoming (Casper) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C)  |  Imperial (°F)

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How hot is it in Casper in September?

Daytime temperatures usually reach 73°F in Casper in September, falling to 41°F at night.

How sunny is it in Casper in September?

There are normally 9 hours of bright sunshine each day in Casper in September - that's 70% of daylight hours.

Does it rain in Casper in September?

There are usually 7 days with some rain in Casper in September and the average monthly rainfall is 0.9 inches.

Casper September sunrise & sunset times

Browse the sunrise and sunset times for Casper in September 2025. Select a month to view Casper sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:30 18:39
Monday, 15th September 2025 05:45 18:14
Tuesday, 30th September 2025 06:02 17:48

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