South Mountain Reservoir Weather Forecast

    • 36
    • 60

    Becoming Sunny

    • 41
    • 69

    Sunny

    • 44
    • 74

    Mostly Sunny

    • 42
    • 68

    Sunny

    • 42
    • 68

    Sunny

    • 43
    • 71

    Mostly Sunny

    • 45
    • 75

    Mostly Sunny

Today 13 Sep Modoc County

Sunny. Highs in the lower to mid 60s. Northwest Winds 10 to 15 Mph.

Tonight 13 Sep Modoc County

Clear. Areas of frost well after midnight. Lows in the mid 30s to lower 40s. North Winds 5 to 10 Mph.

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South Mountain Reservoir Temperature Statistics

September Temperature

Alturas (22.4 miles)

  • Lowest 10 September, 2026

    47.6 °F

  • Average September

    69.8 °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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