Decatur weather in August 2025

Expect 29°C daytime maximum temperatures in the shade with on average 9 hours of sunshine per day in Decatur in August. Check more long-term weather averages for Decatur in August before you book your next holiday to Illinois in 2025/2026.

  • 29°C maximum daytime temperature in August in Decatur29
    29°C max day temperature
  • 9 hours of sunshine per day
  • 8 days with some rainfall in August in Decatur8
    8 days with some rainfall
  • 17°C minimum night-time temperature in August in Decatur17
    17°C min night temperature
  • 14 hours of daylight per day in August in Decatur14
    14 hours of daylight per day
  • Moderate heat & humidity in August in DecaturM
    Moderate heat & humidity
  • 93 mm monthly rainfall in August in Decatur93
    93 mm of monthly rainfall
  • UV (maximum) index 8 (Very High) in August in Decatur8
    8 (Very High) UV index

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The August weather guide for Illinois (Decatur) 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 Decatur in August?

Daytime temperatures usually reach 29°C in Decatur in August with moderate heat and humidity, falling to 17°C at night.

How sunny is it in Decatur in August?

There are normally 9 hours of bright sunshine each day in Decatur in August - that's 67% of daylight hours.

Does it rain in Decatur in August?

There are usually 8 days with some rain in Decatur in August and the average monthly rainfall is 93mm.

Decatur August sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Friday, 1st August 2025 04:55 19:09
Saturday, 16th August 2025 05:09 18:50
Sunday, 31st August 2025 05:23 18:28

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