Janesville Weather Forecast

    • 24
    • 39

    Increasing Clouds

    • 42
    • 48

    Mostly Cloudy

    • 37
    • 57

    Partly Sunny

    • 54
    • 61

    Mostly Cloudy

    • 47
    • 67

    Mostly Cloudy

    • 36
    • 56

    Mostly Cloudy

Today 21 Dec Cumberland

Sunny, cooler with Highs in the upper 30s. North Winds around 5 Mph, becoming east this afternoon.

Tonight 21 Dec Cumberland

Mostly clear in the Evening, then becoming partly cloudy. Near steady temperature in the upper 20s. Southeast Winds 5 to 10 Mph.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Janesville Temperature Statistics

December Temperature

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

  • Lowest 14 December, 2025

    -7.1 °F

  • Average December

    25.6 °F

  • Highest 18 December, 2025

    52 °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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