Flathead Lake Weather Forecast

    • 55
    • 70

    Becoming Sunny

    • 55
    • 70

    Mostly Sunny

    • 56
    • 72

    Mostly Sunny

    • 56
    • 71

    Mostly Sunny

    • 55
    • 69

    Partly Sunny

    • 56
    • 70

    Partly Sunny

Today 19 Sep Flathead/Mission Valleys

Mostly sunny. Patchy fog early in the morning. Highs in the 70s.

Tonight 19 Sep Flathead/Mission Valleys

Partly cloudy. Lows in the 40s to lower 50s.

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Flathead Lake Temperature Statistics

September Temperature

Kalispell, Glacier Park International Airport (30.4 miles)

  • Lowest 1 September, 2026

    41.6 °F

  • Average September

    56.8 °F

  • Highest 1 September, 2026

    84.7 °F

Climate (2021–2026)

Kalispell, Glacier Park International Airport (30.4 miles)

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  • Average Low 2021–2026

    33.4 °F

  • Average 2021–2026

    45.4 °F

  • Average High 2021–2026

    57 °F
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