South Mountain Reservoir Weather Forecast

    • 46
    • 78

    Mostly Cloudy

    • 43
    • 76

    Mostly Sunny

    • 48
    • 78

    Partly Sunny

    • 46
    • 77

    Partly Sunny

    • 39
    • 67

    Slight Chance Rain

    • 41
    • 67

    Partly Sunny

    • 38
    • 66

    Mostly Sunny

Today 21 Sep Modoc County

Mostly clear. Lows in the mid 30s to lower 40s. Highs in the mid 60s to lower 70s.

Tonight 21 Sep Modoc County

Partly cloudy then becoming mostly clear after midnight then becoming partly cloudy. Lows in the mid 40s to lower 50s. Northwest Winds 5 to 10 Mph.

Graph Plots Open in Graphs

  • Temperature Forecast NOAA

  • Temperature Real-Time

South Mountain Reservoir Temperature Statistics

September Temperature

Alturas (22.4 miles)

  • Lowest 14 September, 2026

    28.7 °F

  • Average September

    58.3 °F

  • Highest 10 September, 2026

    85.6 °F

Climate (2021–2026)

Alturas (22.4 miles)

Take a look at our website widgetsAvailable free! Find Out More

  • Average Low 2021–2026

    33.2 °F

  • Average 2021–2026

    49.1 °F

  • Average High 2021–2026

    64.7 °F
Get WillyWeather+ to remove ads