Janesville Weather Forecast

    • 65
    • 93

    Mostly Sunny

    • 64
    • 91

    Mostly Sunny

    • 63
    • 91

    Mostly Sunny

    • 64
    • 93

    Partly Sunny

    • 63
    • 89

    Mostly Cloudy

    • 58
    • 84

    Chance Rain Showers

Today 14 Sep Cumberland

Sunny. Highs in the lower 90s. South Winds around 5 Mph, becoming northeast in the afternoon.

Tonight 14 Sep Cumberland

Mostly clear. Lows in the mid 60s. East Winds around 5 Mph.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Janesville Temperature Statistics

September Temperature

Mattoon / Charleston, Coles County Memorial Airport (6.8 miles)

  • Lowest 7 September, 2025

    45 °F

  • Average September

    65.1 °F

  • Highest 11 September, 2025

    86 °F

Climate (2020–Present)

Mattoon / Charleston, Coles County Memorial Airport (6.8 miles)

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  • Average Low 2020–2025

    45.7 °F

  • Average 2020–2025

    55.1 °F

  • Average High 2020–2025

    64.5 °F
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