Illiopolis Weather Forecast

    • 55
    • 80

    Mostly Sunny

    • 57
    • 81

    Mostly Sunny

    • 65
    • 82

    Rain Showers Likely

    • 63
    • 83

    Rain Showers Likely

    • 63
    • 84

    Chance Thunderstorms

    • 61
    • 79

    Slight Chance Thunderstorms

    • 58
    • 76

    Slight Chance Thunderstorms

Today 24 May Sangamon

Sunny. Near steady temperature in the upper 70s. North Winds around 5 Mph.

Tonight 24 May Sangamon

Mostly clear. Patchy fog after midnight. Lows in the mid 50s. East Winds around 5 Mph in the Evening, becoming light and variable.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Illiopolis Temperature Statistics

May Temperature

Decatur Airport (19.3 miles)

  • Lowest 7 May, 2026

    37.7 °F

  • Average May

    60 °F

  • Highest 17 May, 2026

    82 °F

Climate (2021–Present)

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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