San Clemente Island - Northwest Harbor Weather Forecast

    • 62
    • 70

    Patchy Fog

    • 63
    • 70

    Mostly Cloudy

    • 63
    • 72

    Partly Sunny

    • 63
    • 70

    Mostly Cloudy

    • 62
    • 71

    Mostly Cloudy

    • 62
    • 70

    Mostly Cloudy

    • 62
    • 70

    Mostly Cloudy

Today 5 Sep Catalina and Santa Barbara Islands

Areas of low Clouds and fog in the morning then sunny. Highs from the upper 60s to mid 70s near the coast to the upper 70s to mid 80s interior.

Tonight 5 Sep Catalina and Santa Barbara Islands

Low Clouds and fog near the coast early Spreading inland. Lows in the lower 60s.

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San Clemente Island - Northwest Harbor Temperature Statistics

September Temperature

San Clemente Island NALF (0.6 miles)

  • Lowest 1 September, 2025

    64 °F

  • Average September

    68.6 °F

  • Highest 1 September, 2025

    73 °F

Climate (2020–Present)

San Clemente Island NALF (0.6 miles)

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  • Average Low 2020–2025

    56.8 °F

  • Average 2020–2025

    61.3 °F

  • Average High 2020–2025

    66.1 °F
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