San Juan Island - Roche Harbor Weather Forecast

    • 54
    • 65

    Slight Chance Rain

    • 55
    • 66

    Mostly Sunny

    • 55
    • 68

    Partly Sunny

    • 53
    • 68

    Partly Sunny

    • 53
    • 64

    Chance Rain

    • 53
    • 65

    Mostly Sunny

Today 7 Sep San Juan County

Mostly cloudy with a chance of rain in the Morning, then mostly cloudy with a slight chance of rain late in the morning. Mostly sunny in the afternoon. Highs in the 60s. South wind around 10 Mph.

Tonight 7 Sep San Juan County

Partly cloudy. Lows in the upper 40s to mid 50s. South wind to 10 Mph in the evening becoming light.

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San Juan Island - Roche Harbor Temperature Statistics

September Temperature

Friday Harbor Airport (8.1 miles)

  • Lowest 3 September, 2026

    48.9 °F

  • Average September

    58.3 °F

  • Highest 5 September, 2026

    70 °F

Climate (2021–2026)

Friday Harbor Airport (8.1 miles)

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  • Average Low 2021–2026

    44.5 °F

  • Average 2021–2026

    51.9 °F

  • Average High 2021–2026

    59.7 °F
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