Great South Bay Weather Forecast

    • 59
    • 70

    Chance Rain

    • 59
    • 66

    Chance Rain

    • 59
    • 65

    Windy

    • 57
    • 64

    Chance Rain Showers

    • 59
    • 64

    Chance Rain Showers

    • 60
    • 65

    Chance Rain Showers

Today 21 Sep Southwest Suffolk

Partly sunny. Highs around 70. Northeast Winds 15 to 20 Mph with Gusts up to 30 Mph.

Tonight 21 Sep Southwest Suffolk

Cloudy. A slight chance of rain after midnight. Lows in the upper 50s. Northeast Winds 15 to 20 Mph with Gusts up to 30 Mph. 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 15 September, 2026

    52.6 °F

  • Average September

    71 °F

  • Highest 10 September, 2026

    86.6 °F

Climate (2021–2026)

Islip, Long Island Mac Arthur Airport (8.1 miles)

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  • Average Low 2021–2026

    47.2 °F

  • Average 2021–2026

    55.2 °F

  • Average High 2021–2026

    63.1 °F
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