Round Lake Weather Forecast

    • 61
    • 82

    Chance Thunderstorms

    • 64
    • 87

    Chance Thunderstorms

    • 63
    • 82

    Rain Showers

    • 61
    • 80

    Rain Showers

    • 52
    • 77

    Partly Sunny

    • 48
    • 72

    Breezy

    • 51
    • 75

    Partly Sunny

Today 4 Sep McHenry

Mostly sunny. Highs around 80. East Winds 10 to 15 Mph with Gusts up to 25 Mph.

Tonight 4 Sep McHenry

Partly cloudy. A slight chance of Showers and Thunderstorms in the Evening, then a chance of Showers and Thunderstorms after midnight. Lows around 60. East Winds around 15 Mph with Gusts up to 30 Mph. Chance of rain 30 percent.

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  • Temperature Forecast NOAA

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Round Lake Temperature Statistics

September Temperature

Harvey Municipal Airport (23 miles)

  • Lowest 2 September, 2026

    50 °F

  • Average September

    66.2 °F

  • Highest 2 September, 2026

    82.4 °F

Climate (2021–2026)

Harvey Municipal Airport (23 miles)

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  • Average Low 2021–2026

    30.3 °F

  • Average 2021–2026

    41.2 °F

  • Average High 2021–2026

    51.8 °F
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