Rapid City weather in September 2025

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

  • 73°F maximum daytime temperature in September in Rapid City73
    73°F max day temperature
  • 9 hours of sunshine per day
  • 7 days with some rainfall in September in Rapid City7
    7 days with some rainfall
  • 45°F minimum night-time temperature in September in Rapid City45
    45°F min night temperature
  • 12 hours of daylight per day in September in Rapid City12
    12 hours of daylight per day
  • No heat & humidity in September in Rapid City0
    No heat & humidity
  • 1.2 inches monthly rainfall in September in Rapid City1.2
    1.2 inches of monthly rainfall
  • UV (maximum) index 6 (High) in September in Rapid City6
    6 (High) UV index

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The September weather guide for South Dakota (Rapid City) 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 Rapid City in September?

Daytime temperatures usually reach 73°F in Rapid City in September, falling to 45°F at night.

How sunny is it in Rapid City in September?

There are normally 9 hours of bright sunshine each day in Rapid City in September - that's 69% of daylight hours.

Does it rain in Rapid City in September?

There are usually 7 days with some rain in Rapid City in September and the average monthly rainfall is 1.2 inches.

Rapid City September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:16 18:28
Monday, 15th September 2025 05:32 18:03
Tuesday, 30th September 2025 05:50 17:35

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