Flat Lake Weather Forecast

    • 47
    • 64

    Rain Showers Likely

    • 45
    • 70

    Rain Showers

    • 43
    • 63

    Breezy

    • 44
    • 65

    Chance Rain Showers

    • 47
    • 70

    Partly Sunny

    • 47
    • 73

    Partly Sunny

Today 13 Sep McHenry

Sunny. Highs in the lower 60s. Northwest Winds around 5 Mph in the Morning, becoming light and variable.

Tonight 13 Sep McHenry

Mostly clear in the Evening, then partly cloudy with Showers likely after midnight. Lows in the upper 40s. East Winds 5 to 10 Mph with Gusts up to 20 Mph, increasing to southeast 15 to 20 Mph with Gusts up to 35 Mph after midnight. Chance of rain 70 percent.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Flat Lake Temperature Statistics

September Temperature

Harvey Municipal Airport (22.4 miles)

  • Lowest 2 September, 2026

    50 °F

  • Average September

    67.3 °F

  • Highest 4 September, 2026

    84.2 °F

Climate (2021–2026)

Harvey Municipal Airport (22.4 miles)

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  • Average Low 2021–2026

    30.4 °F

  • Average 2021–2026

    41.2 °F

  • Average High 2021–2026

    51.8 °F
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