Illiopolis Weather Forecast

    • 59
    • 78

    Chance Thunderstorms

    • 51
    • 77

    Severe Tstms

    • 47
    • 67

    Chance Rain Showers

    • 42
    • 65

    Mostly Sunny

    • 43
    • 66

    Partly Sunny

    • 40
    • 63

    Partly Sunny

    • 45
    • 66

    Partly Sunny

Today 26 Apr Sangamon

Mostly sunny. Near steady temperature in the upper 70s. Southeast Winds 10 to 15 Mph.

Tonight 26 Apr Sangamon

Partly cloudy in the Evening, then mostly cloudy with a chance of Showers and Thunderstorms after midnight. Not as cool with Lows in the upper 50s. Southeast Winds 10 to 15 Mph. Gusts up to 30 Mph after midnight. Chance of rain 40 percent.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Illiopolis Temperature Statistics

April Temperature

Decatur Airport (19.3 miles)

  • Lowest 7 April, 2026

    34.6 °F

  • Average April

    59.6 °F

  • Highest 14 April, 2026

    83.6 °F

Climate (2021–Present)

Decatur Airport (19.3 miles)

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  • Average Low 2021–2026

    45.4 °F

  • Average 2021–2026

    55.5 °F

  • Average High 2021–2026

    65.5 °F
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