Johnstown Weather Forecast

    • 54
    • 73

    Areas Smoke

    • 50
    • 75

    Mostly Sunny

    • 54
    • 78

    Partly Sunny

    • 57
    • 78

    Partly Sunny

    • 60
    • 79

    Partly Sunny

    • 61
    • 81

    Slight Chance Thunderstorms

Today 31 Jul Rock

Mostly sunny. Areas of smoke through the day. Highs in the mid 70s. Northeast Winds 10 to 15 Mph.

Tonight 31 Jul Rock

Partly cloudy. Lows in the lower 50s. Northeast Winds 5 to 10 Mph.

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Johnstown Temperature Statistics

July Temperature

Janesville-Rock County (13 miles)

  • Lowest 18 July, 2025

    50 °F

  • Average July

    71.3 °F

  • Highest 23 July, 2025

    91.4 °F

Climate (2020–Present)

Janesville-Rock County (13 miles)

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  • Average Low 2020–2025

    40.5 °F

  • Average 2020–2025

    48.8 °F

  • Average High 2020–2025

    60.3 °F
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