Great South Bay Weather Forecast

    • 58
    • 78

    Partly Sunny

    • 63
    • 68

    Mostly Cloudy

    • 65
    • 70

    Rain Showers Likely

    • 61
    • 68

    Chance Rain Showers

    • 59
    • 64

    Chance Rain Showers

    • 59
    • 63

    Slight Chance Rain Showers

Today 18 Sep Southwest Suffolk

Mostly sunny. Highs around 80. North Winds 5 to 10 Mph.

Tonight 18 Sep Southwest Suffolk

Partly cloudy. Less humid with Lows in the mid 50s. North Winds 10 to 15 Mph with Gusts up to 25 Mph.

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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

    53.1 °F

  • Average September

    71.5 °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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