San Juan Island - Grandmas Cove Weather Forecast

    • 52
    • 66

    Mostly Sunny

    • 53
    • 67

    Partly Sunny

    • 53
    • 67

    Mostly Sunny

    • 53
    • 69

    Mostly Sunny

    • 53
    • 69

    Partly Sunny

    • 53
    • 68

    Mostly Cloudy

Today 10 Aug San Juan County

Sunny. Highs in the mid 60s to lower 70s. Light wind becoming south to 10 Mph in the afternoon.

Tonight 10 Aug San Juan County

Mostly clear. Lows in the 50s. South wind to 10 Mph becoming southwest after midnight.

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  • Temperature Real-Time

San Juan Island - Grandmas Cove Temperature Statistics

August Temperature

Friday Harbor Airport (3.7 miles)

  • Lowest 3 August, 2026

    48.9 °F

  • Average August

    62.5 °F

  • Highest 4 August, 2026

    78.1 °F

Climate (2021–2026)

Friday Harbor Airport (3.7 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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