Mill Valley Weather Forecast

    • 54
    • 72

    Mostly Sunny

    • 56
    • 75

    Partly Sunny

    • 57
    • 75

    Chance Rain Showers

    • 56
    • 75

    Chance Rain Showers

    • 55
    • 75

    Slight Chance Rain Showers

    • 54
    • 74

    Mostly Sunny

    • 55
    • 75

    Mostly Sunny

Today 6 Sep North Bay Interior Valleys

Sunny. Highs in the upper 60s to mid 80s. West Winds 10 to 20 Mph.

Tonight 6 Sep North Bay Interior Valleys

Mostly clear in the evening then becoming partly cloudy. Patchy fog after midnight. Lows in the 50s. West Winds 5 to 15 Mph.

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Mill Valley Temperature Statistics

September Temperature

Novato / Gnoss Field (16.2 miles)

  • Lowest 1 September, 2025

    51.8 °F

  • Average September

    64.8 °F

  • Highest 1 September, 2025

    89.6 °F

Climate (2020–Present)

Novato / Gnoss Field (16.2 miles)

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  • Average Low 2020–2025

    46 °F

  • Average 2020–2025

    57.4 °F

  • Average High 2020–2025

    72.6 °F
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