Great Diamond Island Weather Forecast

    • 4
    • 23

    Decreasing Clouds

    • 3
    • 16

    Partly Sunny

    • 8
    • 20

    Partly Sunny

    • 18
    • 25

    Blustery

    • 16
    • 32

    Partly Sunny

    • 16
    • 32

    Partly Sunny

Today 29 Jan Coastal Cumberland

Partly sunny. Highs in the lower 20s. Northwest Winds 10 to 15 Mph. Wind chill Values as low as 11 below in the morning.

Tonight 29 Jan Coastal Cumberland

Mostly cloudy. Lows around 2 above. Light and variable Winds.

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Great Diamond Island Temperature Statistics

January Temperature

Portland, Portland International Jetport (5 miles)

  • Lowest 25 January, 2026

    -5.1 °F

  • Average January

    24.3 °F

  • Highest 14 January, 2026

    48.7 °F

Climate (2021–Present)

Portland, Portland International Jetport (5 miles)

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  • Average Low 2021–2026

    40.3 °F

  • Average 2021–2026

    48.8 °F

  • Average High 2021–2026

    57.2 °F
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