Lake Riverside Weather Forecast

    • 50
    • 81

    Partly Sunny

    • 45
    • 74

    Becoming Sunny

    • 53
    • 78

    Mostly Sunny

    • 58
    • 87

    Sunny

    • 58
    • 88

    Mostly Sunny

    • 55
    • 86

    Mostly Sunny

    • 54
    • 84

    Partly Sunny

Today 20 Sep Riverside County Mountains

Partly cloudy in the morning. Becoming mostly sunny. Highs 75 to 85.

Tonight 20 Sep Riverside County Mountains

Partly cloudy. Cooler. Lows 46 to 56. Light Winds.

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Lake Riverside Temperature Statistics

September Temperature

Big Bear City Airport (51.6 miles)

  • Lowest 18 September, 2026

    37.2 °F

  • Average September

    61.2 °F

  • Highest 10 September, 2026

    81.3 °F

Climate (2021–2026)

Big Bear City Airport (51.6 miles)

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  • Average Low 2021–2026

    33.8 °F

  • Average 2021–2026

    48.8 °F

  • Average High 2021–2026

    60.4 °F
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