Castle Island Weather Forecast

    • 56
    • 71

    Partly Sunny

    • 56
    • 71

    Partly Sunny

    • 61
    • 72

    Slight Chance Rain Showers

    • 63
    • 77

    Slight Chance Rain Showers

    • 53
    • 77

    Mostly Sunny

    • 50
    • 65

    Mostly Sunny

Today 15 Sep Suffolk

Mostly sunny. Highs in the lower 70s. East Winds 5 to 10 Mph with Gusts up to 20 Mph.

Tonight 15 Sep Suffolk

Partly cloudy. Patchy fog after midnight. Lows in the mid 50s. Southeast Winds 5 to 10 Mph, becoming northwest after midnight.

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Castle Island Temperature Statistics

September Temperature

Boston, Logan International Airport (1.2 miles)

  • Lowest 9 September, 2025

    54 °F

  • Average September

    65.6 °F

  • Highest 6 September, 2025

    86 °F

Climate (2020–Present)

Boston, Logan International Airport (1.2 miles)

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  • Average Low 2020–2025

    46.9 °F

  • Average 2020–2025

    53.8 °F

  • Average High 2020–2025

    61.1 °F
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