Great South Bay Weather Forecast

    • 69
    • 72

    Chance Rain Showers

    • 71
    • 74

    Mostly Sunny

    • 62
    • 78

    Rain Showers Likely

    • 58
    • 71

    Chance Rain Showers

    • 57
    • 72

    Mostly Sunny

    • 58
    • 71

    Partly Sunny

    • 58
    • 70

    Partly Sunny

Today 4 Sep Southwest Suffolk

Sunny. Near steady temperature in the lower 70s. South Winds 10 to 15 Mph with Gusts up to 25 Mph.

Tonight 4 Sep Southwest Suffolk

Mostly cloudy with a chance of Showers with a slight chance of Thunderstorms. Breezy with Lows in the mid 60s. South Winds 15 to 25 Mph with Gusts up to 35 Mph. Chance of rain 50 percent.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Great South Bay Temperature Statistics

September Temperature

Islip, Long Island Mac Arthur Airport (8.1 miles)

  • Lowest 2 September, 2025

    57.9 °F

  • Average September

    67.6 °F

  • Highest 1 September, 2025

    77 °F

Climate (2020–Present)

Islip, Long Island Mac Arthur Airport (8.1 miles)

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  • Average Low 2020–2025

    47.4 °F

  • Average 2020–2025

    55.2 °F

  • Average High 2020–2025

    63.1 °F
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