Mount Diablo State Park Weather Forecast

    • 54
    • 76

    Increasing Clouds

    • 54
    • 65

    Mostly Cloudy

    • 54
    • 67

    Mostly Sunny

    • 56
    • 69

    Mostly Sunny

    • 68
    • 81

    Mostly Sunny

    • 67
    • 84

    Mostly Sunny

Today 19 Sep East Bay Hills

Sunny. Highs in the mid 80s. North Winds around 5 Mph. Becoming west in the afternoon.

Tonight 19 Sep East Bay Hills

Mostly clear in the evening then becoming mostly cloudy. Lows in the upper 50s. Southwest Winds 10 to 15 Mph.

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Mount Diablo State Park Temperature Statistics

September Temperature

Concord, Buchanan Field (10.6 miles)

  • Lowest 7 September, 2026

    54.6 °F

  • Average September

    72 °F

  • Highest 9 September, 2026

    101.6 °F

Climate (2021–2026)

Concord, Buchanan Field (10.6 miles)

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  • Average Low 2021–2026

    51.1 °F

  • Average 2021–2026

    61.6 °F

  • Average High 2021–2026

    74.2 °F
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