Illiopolis Weather Forecast

    • 73
    • 92

    Chance Thunderstorms

    • 70
    • 87

    Thunderstorms Likely

    • 67
    • 85

    Chance Thunderstorms

    • 70
    • 88

    Slight Chance Thunderstorms

    • 69
    • 86

    Chance Thunderstorms

    • 69
    • 86

    Chance Thunderstorms

    • 70
    • 87

    Chance Thunderstorms

Today 5 Jul Sangamon

Sunny. Near steady temperature in the lower 90s. South Winds 10 to 15 Mph.

Tonight 5 Jul Sangamon

Partly cloudy with a slight chance of Showers and Thunderstorms this Evening, then mostly cloudy with a chance of Showers and Thunderstorms after midnight. Lows in the lower 70s. Southwest Winds 5 to 10 Mph. Chance of rain 40 percent.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Illiopolis Temperature Statistics

July Temperature

Decatur Airport (19.3 miles)

  • Lowest 2 July, 2025

    66.9 °F

  • Average July

    79.8 °F

  • Highest 3 July, 2025

    90 °F

Climate (2020–Present)

Decatur Airport (19.3 miles)

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  • Average Low 2020–2025

    45.1 °F

  • Average 2020–2025

    55.1 °F

  • Average High 2020–2025

    64.9 °F
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