Sister Island Weather Forecast

    • 59
    • 67

    Rain Showers

    • 48
    • 70

    Mostly Sunny

    • 51
    • 62

    Partly Sunny

    • 49
    • 59

    Chance Rain Showers

    • 48
    • 64

    Partly Sunny

    • 47
    • 62

    Mostly Sunny

Today 17 Sep Coastal Cumberland

Mostly cloudy. A chance of Sprinkles this Morning, then a slight chance of Showers this afternoon. Highs around 70. Light and variable Winds. Chance of rain 20 percent.

Tonight 17 Sep Coastal Cumberland

Showers. Patchy fog. Lows in the mid 50s. Light and variable Winds. Chance of rain 90 percent.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Sister Island Temperature Statistics

September Temperature

Portland, Portland International Jetport (17.4 miles)

  • Lowest 12 September, 2026

    43.6 °F

  • Average September

    64.6 °F

  • Highest 10 September, 2026

    85.6 °F

Climate (2021–2026)

Portland, Portland International Jetport (17.4 miles)

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  • Average Low 2021–2026

    40 °F

  • Average 2021–2026

    48.7 °F

  • Average High 2021–2026

    57.3 °F
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