Castle Island Weather Forecast

    • 64
    • 76

    Becoming Sunny

    • 71
    • 95

    Slight Chance Thunderstorms

    • 54
    • 90

    Rain Showers

    • 49
    • 65

    Partly Sunny

    • 49
    • 61

    Mostly Cloudy

    • 50
    • 62

    Chance Rain Showers

Today 18 May Suffolk

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

Tonight 18 May Suffolk

Partly cloudy. Lows in the mid 50s. Northeast Winds around 5 Mph.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Castle Island Temperature Statistics

May Temperature

Boston, Logan International Airport (1.2 miles)

  • Lowest 9 May, 2026

    42.7 °F

  • Average May

    56.9 °F

  • Highest 5 May, 2026

    79.6 °F

Climate (2021–Present)

Boston, Logan International Airport (1.2 miles)

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  • Average Low 2021–2026

    46.7 °F

  • Average 2021–2026

    53.6 °F

  • Average High 2021–2026

    60.9 °F
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