South Mountain Reservoir Weather Forecast

    • 22
    • 37

    Mostly Sunny

    • 25
    • 42

    Mostly Sunny

    • 27
    • 47

    Mostly Sunny

    • 29
    • 50

    Mostly Cloudy

    • 31
    • 47

    Chance Rain/Snow

    • 29
    • 44

    Rain/Snow Likely

Today 28 Dec Modoc County

Partly cloudy in the morning then becoming sunny. Highs in the mid 30s to lower 40s. Northeast Winds 5 to 10 Mph.

Tonight 28 Dec Modoc County

Mostly clear. Lows 15 to 25. East Winds 5 to 10 Mph.

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South Mountain Reservoir Temperature Statistics

December Temperature

Alturas (22.4 miles)

  • Lowest 1 December, 2025

    15.1 °F

  • Average December

    43.6 °F

  • Highest 10 December, 2025

    64 °F

Climate (2020–Present)

Alturas (22.4 miles)

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  • Average Low 2020–2025

    33.4 °F

  • Average 2020–2025

    49.4 °F

  • Average High 2020–2025

    64.4 °F
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