Casper weather in September 2025

Expect daytime maximum temperatures of 23°C in Casper, Wyoming in September based on long-term weather averages. There are 9 hours of sunshine per day on average.

  • 23°C maximum daytime temperature in September in Casper23
    23°C max day temperature
  • 9 hours of sunshine per day
  • 7 days with some rainfall in September in Casper7
    7 days with some rainfall
  • 5°C minimum night-time temperature in September in Casper5
    5°C 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
  • 24 mm monthly rainfall in September in Casper24
    24 mm 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 / mm)  |  Imperial (°F / inches)

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How hot is it in Casper in September?

Daytime temperatures usually reach 23°C in Casper in September, falling to 5°C 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 24mm.

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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