San Clemente Island - Northwest Harbor Weather Forecast

    • 67
    • 76

    Mostly Sunny

    • 67
    • 75

    Partly Sunny

    • 67
    • 75

    Partly Sunny

    • 70
    • 76

    Partly Sunny

    • 71
    • 76

    Mostly Sunny

    • 72
    • 77

    Mostly Sunny

Today 29 Sep Catalina and Santa Barbara Islands

Sunny. Highs in the upper 70s to mid 80s.

Tonight 29 Sep Catalina and Santa Barbara Islands

Mostly clear. Lows in the upper 50s to mid 60s.

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San Clemente Island - Northwest Harbor Temperature Statistics

September Temperature

San Clemente Island NALF (0.6 miles)

  • Lowest 26 September, 2026

    64.9 °F

  • Average September

    73.3 °F

  • Highest 9 September, 2026

    87.1 °F

Climate (2021–2026)

San Clemente Island NALF (0.6 miles)

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  • Average Low 2021–2026

    57.9 °F

  • Average 2021–2026

    62.4 °F

  • Average High 2021–2026

    66.8 °F
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