Janesville Weather Forecast

    • 65
    • 81

    Increasing Clouds

    • 69
    • 96

    Chance Thunderstorms

    • 71
    • 93

    Chance Rain Showers

    • 68
    • 92

    Slight Chance Thunderstorms

    • 66
    • 88

    Mostly Sunny

    • 64
    • 88

    Chance Rain Showers

Today 14 Sep Cumberland

Mostly sunny. Highs in the lower 80s. East Winds around 10 Mph.

Tonight 14 Sep Cumberland

Mostly clear. Lows in the mid 60s. Southeast Winds around 10 Mph.

Graph Plots Open in Graphs

  • Temperature Forecast NOAA

  • Temperature Real-Time

Janesville Temperature Statistics

September Temperature

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

  • Lowest 7 September, 2026

    57.7 °F

  • Average September

    79.8 °F

  • Highest 2 September, 2026

    97.6 °F

Climate (2021–2026)

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

Take a look at our website widgetsAvailable free! Find Out More

  • Average Low 2021–2026

    45.9 °F

  • Average 2021–2026

    55.5 °F

  • Average High 2021–2026

    65.1 °F
Get WillyWeather+ to remove ads