Duncan Airport Weather Forecast

    • 53
    • 81

    Increasing Clouds

    • 52
    • 81

    Partly Sunny

    • 54
    • 83

    Mostly Sunny

    • 47
    • 75

    Slight Chance Thunderstorms

    • 48
    • 73

    Mostly Sunny

    • 51
    • 81

    Mostly Sunny

Today 18 Sep Upper Blackfoot and MacDonald Pass

Sunny. Highs 70 to 75. West Winds up to 10 Mph.

Tonight 18 Sep Upper Blackfoot and MacDonald Pass

Mostly clear. Lows 45 to 55. North Winds up to 5 Mph shifting to the southwest after midnight.

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Duncan Airport Temperature Statistics

September Temperature

Helena Regional Airport (8.7 miles)

  • Lowest 5 September, 2025

    46 °F

  • Average September

    64.9 °F

  • Highest 3 September, 2025

    91.9 °F

Climate (2020–Present)

Helena Regional Airport (8.7 miles)

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  • Average Low 2020–2025

    36.1 °F

  • Average 2020–2025

    47.5 °F

  • Average High 2020–2025

    59.4 °F
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