Sioux City weather in September 2025

Expect 24°C daytime maximum temperatures in the shade with on average 8 hours of sunshine per day in Sioux City in September. Check more long-term weather averages for Sioux City in September before you book your next holiday to Iowa in 2025/2026.

  • 24°C maximum daytime temperature in September in Sioux City24
    24°C max day temperature
  • 8 hours of sunshine per day
  • 9 days with some rainfall in September in Sioux City9
    9 days with some rainfall
  • 11°C minimum night-time temperature in September in Sioux City11
    11°C min night temperature
  • 12 hours of daylight per day in September in Sioux City12
    12 hours of daylight per day
  • No heat & humidity in September in Sioux City0
    No heat & humidity
  • 73 mm monthly rainfall in September in Sioux City73
    73 mm of monthly rainfall
  • UV (maximum) index 6 (High) in September in Sioux City6
    6 (High) UV index

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The September weather guide for Iowa (Sioux 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 / mm)  |  Imperial (°F / inches)

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How hot is it in Sioux City in September?

Daytime temperatures usually reach 24°C in Sioux City in September, falling to 11°C at night.

How sunny is it in Sioux City in September?

There are normally 8 hours of bright sunshine each day in Sioux City in September - that's 63% of daylight hours.

Does it rain in Sioux City in September?

There are usually 9 days with some rain in Sioux City in September and the average monthly rainfall is 73mm.

Sioux City September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:51 18:59
Monday, 15th September 2025 06:06 18:35
Tuesday, 30th September 2025 06:22 18:08

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