Illiopolis Weather Forecast

    • 75
    • 90

    Slight Chance Thunderstorms

    • 73
    • 90

    Chance Thunderstorms

    • 70
    • 88

    Chance Thunderstorms

    • 66
    • 83

    Rain Showers Likely

    • 67
    • 80

    Chance Rain Showers

    • 68
    • 82

    Chance Rain Showers

Today 10 Aug Sangamon

Mostly sunny. Humid with Highs in the lower 90s. Southwest Winds 5 to 10 Mph. Heat index Values up to 104 in the afternoon.

Tonight 10 Aug Sangamon

Partly cloudy. Humid with Lows in the mid 70s. Southwest Winds 5 to 10 Mph.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Illiopolis Temperature Statistics

August Temperature

Decatur Airport (19.3 miles)

  • Lowest 4 August, 2026

    60.7 °F

  • Average August

    74.1 °F

  • Highest 7 August, 2026

    87.1 °F

Climate (2021–2026)

Decatur Airport (19.3 miles)

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  • Average Low 2021–2026

    45.3 °F

  • Average 2021–2026

    55.5 °F

  • Average High 2021–2026

    65.6 °F
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