Flagstaff Weather Forecast

    • 49
    • 72

    Mostly Sunny

    • 54
    • 81

    Partly Sunny

    • 56
    • 81

    Partly Sunny

    • 55
    • 81

    Slight Chance Thunderstorms

    • 51
    • 80

    Slight Chance Thunderstorms

    • 52
    • 82

    Mostly Sunny

Today 18 Sep Boulder And Jefferson Counties Below 6000 Feet/West Broomfield County

Partly cloudy. Highs in the lower 70s.

Tonight 18 Sep Boulder And Jefferson Counties Below 6000 Feet/West Broomfield County

Mostly clear. Lows in the mid to upper 40s.

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Flagstaff Temperature Statistics

September Temperature

Boulder Municipal Airport (3.7 miles)

  • Lowest 6 September, 2025

    44.6 °F

  • Average September

    68.8 °F

  • Highest 10 September, 2025

    91.4 °F

Climate (2020–Present)

Boulder Municipal Airport (3.7 miles)

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  • Average Low 2020–2025

    40.4 °F

  • Average 2020–2025

    52.6 °F

  • Average High 2020–2025

    65 °F
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