South Mountain Reservoir Weather Forecast

    • 44
    • 71

    Increasing Clouds

    • 45
    • 73

    Mostly Sunny

    • 47
    • 77

    Mostly Sunny

    • 46
    • 79

    Mostly Sunny

    • 46
    • 78

    Mostly Sunny

    • 39
    • 74

    Slight Chance Rain

    • 37
    • 61

    Slight Chance Rain/Snow

Today 20 May Modoc County

Sunny. Highs in the lower to mid 70s. Northwest Winds 5 to 10 Mph.

Tonight 20 May Modoc County

Partly cloudy this evening then clearing. Lows in the lower to mid 40s. North Winds 5 to 10 Mph shifting to the northeast well after midnight.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

South Mountain Reservoir Temperature Statistics

May Temperature

Alturas (22.4 miles)

  • Lowest 14 May, 2026

    28.7 °F

  • Average May

    56 °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

    64.9 °F
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