St Louis weather in September 2025

Expect 27°C daytime maximum temperatures in the shade with on average 8 hours of sunshine per day in St Louis in September. Check more long-term weather averages for St Louis in September before you book your next holiday to Missouri in 2025/2026.

  • 27°C maximum daytime temperature in September in St Louis27
    27°C max day temperature
  • 8 hours of sunshine per day
  • 8 days with some rainfall in September in St Louis8
    8 days with some rainfall
  • 15°C minimum night-time temperature in September in St Louis15
    15°C min night temperature
  • 12 hours of daylight per day in September in St Louis12
    12 hours of daylight per day
  • Low heat & humidity in September in St LouisL
    Low heat & humidity
  • 78 mm monthly rainfall in September in St Louis78
    78 mm of monthly rainfall
  • UV (maximum) index 7 (High) in September in St Louis7
    7 (High) UV index

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The September weather guide for Missouri (St Louis) 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 St Louis in September?

Daytime temperatures usually reach 27°C in St Louis in September with low heat and humidity, falling to 15°C at night.

How sunny is it in St Louis in September?

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

Does it rain in St Louis in September?

There are usually 8 days with some rain in St Louis in September and the average monthly rainfall is 78mm.

St Louis September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:30 18:30
Monday, 15th September 2025 05:43 18:08
Tuesday, 30th September 2025 05:56 17:45

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