South Mountain Reservoir Weather Forecast

    • 27
    • 45

    Mostly Cloudy

    • 30
    • 49

    Slight Chance Snow

    • 30
    • 48

    Partly Sunny

    • 34
    • 51

    Mostly Cloudy

    • 33
    • 54

    Mostly Cloudy

    • 33
    • 56

    Mostly Cloudy

Today 26 Jan Modoc County

Mostly cloudy until early afternoon then becoming partly cloudy. Highs in the mid 40s to lower 50s. South Winds around 5 Mph.

Tonight 26 Jan Modoc County

Partly cloudy. Lows in the mid 20s to lower 30s. South Winds around 5 Mph.

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South Mountain Reservoir Temperature Statistics

January Temperature

Alturas (22.4 miles)

  • Lowest 9 January, 2026

    4.6 °F

  • Average January

    36.8 °F

  • Highest 14 January, 2026

    60.7 °F

Climate (2021–Present)

Alturas (22.4 miles)

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  • Average Low 2021–2026

    33.5 °F

  • Average 2021–2026

    49.5 °F

  • Average High 2021–2026

    64.5 °F
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