Great Falls Weather Forecast

    • 52
    • 74

    Rain Likely

    • 49
    • 76

    Slight Chance Thunderstorms

    • 48
    • 80

    Sunny

    • 48
    • 81

    Mostly Sunny

    • 47
    • 76

    Partly Sunny

    • 50
    • 80

    Partly Sunny

Today 15 Sep Cascade County below 5000ft

Not as warm. Partly cloudy with slight chance of rain Showers in the Morning, then mostly cloudy with chance of rain Showers in the afternoon. Highs 70 to 75. West Winds 5 to 15 Mph. Chance of Showers 50 percent.

Tonight 15 Sep Cascade County below 5000ft

Rain Showers likely and chance of Thunderstorms in the Evening, then rain Showers likely and slight chance of Thunderstorms after midnight. Lows 50 to 55. West Winds up to 10 Mph. Chance of precipitation 70 percent.

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Great Falls Temperature Statistics

September Temperature

Great Falls, Great Falls International Airport (3.7 miles)

  • Lowest 5 September, 2025

    39.9 °F

  • Average September

    65.6 °F

  • Highest 1 September, 2025

    90 °F

Climate (2020–Present)

Great Falls, Great Falls International Airport (3.7 miles)

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  • Average Low 2020–2025

    34 °F

  • Average 2020–2025

    46.4 °F

  • Average High 2020–2025

    58.3 °F
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