Big Arm State Park Weather Forecast

    • 53
    • 71

    Mostly Sunny

    • 54
    • 73

    Mostly Sunny

    • 53
    • 73

    Partly Sunny

    • 52
    • 70

    Partly Sunny

    • 54
    • 69

    Partly Sunny

    • 49
    • 65

    Mostly Cloudy

    • 45
    • 55

    Mostly Cloudy

Today 20 Sep Flathead/Mission Valleys

Mostly cloudy. Highs in the mid 50s to lower 60s.

Tonight 20 Sep Flathead/Mission Valleys

Mostly clear. Patchy fog after midnight. Lows in the 40s to lower 50s.

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Big Arm State Park Temperature Statistics

September Temperature

Kalispell, Glacier Park International Airport (33.6 miles)

  • Lowest 17 September, 2026

    38.6 °F

  • Average September

    56.9 °F

  • Highest 1 September, 2026

    84.7 °F

Climate (2021–2026)

Kalispell, Glacier Park International Airport (33.6 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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