Janesville Weather Forecast

    • 36
    • 54

    Mostly Cloudy

    • 15
    • 37

    Breezy

    • 20
    • 28

    Partly Sunny

    • 16
    • 37

    Chance Snow

    • 7
    • 23

    Mostly Cloudy

    • 9
    • 19

    Partly Sunny

Today 13 Jan Cumberland

Mostly sunny. Highs in the mid 50s. Southwest Winds 15 to 20 Mph with Gusts up to 30 Mph.

Tonight 13 Jan Cumberland

Mostly cloudy. Lows in the upper 30s. West Winds 5 to 10 Mph with Gusts up to 20 Mph.

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  • Temperature Real-Time

Janesville Temperature Statistics

January Temperature

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

  • Lowest 4 January, 2026

    21.9 °F

  • Average January

    38.2 °F

  • Highest 8 January, 2026

    64 °F

Climate (2021–Present)

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

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  • Average Low 2021–2026

    45.8 °F

  • Average 2021–2026

    55.2 °F

  • Average High 2021–2026

    64.6 °F
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