Great South Bay Weather Forecast

    • 58
    • 70

    Slight Chance Rain Showers

    • 63
    • 76

    Mostly Sunny

    • 69
    • 77

    Partly Sunny

    • 73
    • 76

    Chance Rain Showers

    • 69
    • 80

    Partly Sunny

    • 66
    • 74

    Mostly Sunny

    • 68
    • 73

    Mostly Sunny

Today 6 Sep Southwest Suffolk

Partly sunny with a 30 percent chance of Showers. Near steady temperature in the lower 70s. Northeast Winds 5 to 10 Mph.

Tonight 6 Sep Southwest Suffolk

Partly cloudy with a slight chance of Showers in the Evening, then clear after midnight. Lows in the upper 50s. South Winds around 5 Mph, becoming northwest after midnight. Chance of rain 20 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, 2026

    65.6 °F

  • Average September

    74.6 °F

  • Highest 3 September, 2026

    85.6 °F

Climate (2021–2026)

Islip, Long Island Mac Arthur Airport (8.1 miles)

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  • Average Low 2021–2026

    47.3 °F

  • Average 2021–2026

    55.2 °F

  • Average High 2021–2026

    63.1 °F
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