South Mountain Reservoir Weather Forecast

    • 42
    • 63

    Chance Rain

    • 41
    • 68

    Mostly Sunny

    • 46
    • 73

    Mostly Sunny

    • 48
    • 77

    Mostly Sunny

    • 48
    • 79

    Mostly Sunny

    • 46
    • 78

    Mostly Sunny

Today 17 Sep Modoc County

Mostly cloudy. Slight chance of Showers in the Morning, then slight chance of Thunderstorms in the afternoon. Highs in the lower to mid 60s. Southwest Winds 5 to 10 Mph shifting to the west late in the afternoon. Chance of precipitation 20 percent.

Tonight 17 Sep Modoc County

Mostly cloudy. A 30 percent chance of Showers in the evening. Lows in the lower to mid 40s. West Winds 5 to 10 Mph.

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South Mountain Reservoir Temperature Statistics

September Temperature

Alturas (22.4 miles)

  • Lowest 14 September, 2026

    32 °F

  • Average September

    59.9 °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

    64.6 °F
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