Boulder Weather Forecast

    • 47
    • 73

    Chance Rain Showers

    • 47
    • 76

    Chance Rain Showers

    • 44
    • 62

    Rain Showers Likely

    • 45
    • 68

    Slight Chance Rain Showers

    • 47
    • 77

    Mostly Sunny

    • 46
    • 75

    Partly Sunny

    • 45
    • 73

    Chance Rain Showers

Today 13 Sep Elkhorn and Boulder Mountains

Partly cloudy in the Morning, then mostly cloudy with a 20 percent chance of Thunderstorms in the afternoon. Highs 60 to 70. Northwest Winds up to 5 Mph shifting to the southeast in the afternoon.

Tonight 13 Sep Elkhorn and Boulder Mountains

Partly cloudy. Chance of rain Showers and slight chance of Thunderstorms in the evening. Lows 40 to 50. West Winds up to 10 Mph. Chance of precipitation 40 percent.

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Boulder Temperature Statistics

September Temperature

Helena Regional Airport (26.1 miles)

  • Lowest 5 September, 2025

    46 °F

  • Average September

    66.8 °F

  • Highest 3 September, 2025

    91.9 °F

Climate (2020–Present)

Helena Regional Airport (26.1 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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