Great South Bay Weather Forecast

    • 63
    • 69

    Partly Sunny

    • 62
    • 71

    Rain

    • 61
    • 67

    Chance Rain

    • 60
    • 64

    Chance Rain Showers

    • 60
    • 64

    Windy

    • 59
    • 64

    Chance Rain Showers

Today 19 Sep Southwest Suffolk

Partly sunny. Highs around 70. Northeast Winds 10 to 15 Mph, becoming east this afternoon. Gusts up to 25 Mph.

Tonight 19 Sep Southwest Suffolk

Partly cloudy in the Evening, then becoming mostly cloudy. Lows in the upper 50s. Southeast Winds 5 to 10 Mph.

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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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