South Mountain Reservoir Weather Forecast

    • 44
    • 74

    Increasing Clouds

    • 46
    • 78

    Partly Sunny

    • 47
    • 79

    Partly Sunny

    • 46
    • 79

    Mostly Sunny

    • 45
    • 79

    Mostly Sunny

    • 46
    • 79

    Mostly Sunny

Today 19 Sep Modoc County

Sunny. Highs in the lower 70s to lower 80s. Northeast Winds around 5 Mph.

Tonight 19 Sep Modoc County

Mostly clear. Lows in the lower to mid 40s. Northeast Winds 5 to 10 Mph shifting to the east well after midnight.

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  • Temperature Real-Time

South Mountain Reservoir Temperature Statistics

September Temperature

Alturas (22.4 miles)

  • Lowest 14 September, 2026

    28.7 °F

  • Average September

    58.8 °F

  • Highest 10 September, 2026

    85.6 °F

Climate (2021–2026)

Alturas (22.4 miles)

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  • Average Low 2021–2026

    33.2 °F

  • Average 2021–2026

    49.1 °F

  • Average High 2021–2026

    64.7 °F
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