Great Diamond Island Weather Forecast

    • 35
    • 38

    Chance Rain

    • 43
    • 48

    Rain

    • 21
    • 46

    Slight Chance Rain Showers

    • 27
    • 33

    Mostly Cloudy

    • 31
    • 39

    Mostly Cloudy

    • 31
    • 43

    Chance Rain/Snow

    • 29
    • 42

    Chance Rain/Snow

Today 15 Mar Coastal Cumberland

Partly sunny. Highs around 40. Light and variable Winds.

Tonight 15 Mar Coastal Cumberland

Cloudy. A slight chance of rain after midnight. Lows in the lower 30s. Southeast Winds around 10 Mph with Gusts up to 25 Mph. Chance of rain 20 percent.

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Great Diamond Island Temperature Statistics

March Temperature

Portland, Portland International Jetport (5 miles)

  • Lowest 2 March, 2026

    4.6 °F

  • Average March

    34.2 °F

  • Highest 10 March, 2026

    66 °F

Climate (2021–Present)

Portland, Portland International Jetport (5 miles)

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  • Average Low 2021–2026

    40.2 °F

  • Average 2021–2026

    48.8 °F

  • Average High 2021–2026

    57.2 °F
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