South Mountain Reservoir Weather Forecast

    • 31
    • 55

    Sunny

    • 30
    • 54

    Partly Sunny

    • 29
    • 53

    Partly Sunny

    • 29
    • 51

    Mostly Sunny

    • 31
    • 48

    Partly Sunny

    • 29
    • 49

    Partly Sunny

Today 19 Jan Modoc County

Sunny. Highs in the lower to mid 50s. Northeast Winds 5 to 10 Mph.

Tonight 19 Jan Modoc County

Mostly clear. Lows in the mid 20s to lower 30s. East Winds 5 to 10 Mph.

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South Mountain Reservoir Temperature Statistics

January Temperature

Alturas (22.4 miles)

  • Lowest 9 January, 2026

    9 °F

  • Average January

    37.5 °F

  • Highest 14 January, 2026

    59 °F

Climate (2021–Present)

Alturas (22.4 miles)

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  • Average Low 2021–2026

    33.5 °F

  • Average 2021–2026

    49.4 °F

  • Average High 2021–2026

    64.5 °F
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