South Mountain Reservoir Weather Forecast

    • 37
    • 60

    Becoming Sunny

    • 39
    • 64

    Mostly Sunny

    • 44
    • 70

    Mostly Sunny

    • 47
    • 76

    Partly Sunny

    • 43
    • 72

    Mostly Sunny

    • 44
    • 73

    Mostly Sunny

Today 30 May Modoc County

Mostly cloudy with a slight chance of rain early this Morning, then partly cloudy in the late morning and early afternoon. Sunny with a slight chance of rain late this afternoon. Highs in the lower to mid 60s. Light Winds becoming west 5 to 10 Mph in the late morning and afternoon. Chance of rain 10 percent.

Tonight 30 May Modoc County

Mostly clear. Lows in the mid 30s to lower 40s. Northwest Winds 5 to 10 Mph shifting to the north well after midnight.

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South Mountain Reservoir Temperature Statistics

May Temperature

Alturas (22.4 miles)

  • Lowest 19 May, 2026

    27.6 °F

  • Average May

    55.8 °F

  • Highest 12 May, 2026

    88.6 °F

Climate (2021–Present)

Alturas (22.4 miles)

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  • Average Low 2021–2026

    33.5 °F

  • Average 2021–2026

    49.6 °F

  • Average High 2021–2026

    65 °F
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