Great South Bay Weather Forecast

    • 60
    • 68

    Mostly Cloudy

    • 64
    • 69

    Partly Sunny

    • 68
    • 71

    Partly Sunny

    • 63
    • 73

    Chance Rain Showers

    • 60
    • 67

    Chance Rain Showers

    • 59
    • 65

    Chance Rain Showers

Today 29 Sep Southwest Suffolk

Mostly cloudy. Highs around 70. Northwest Winds 5 to 10 Mph.

Tonight 29 Sep Southwest Suffolk

Mostly cloudy in the Evening, then becoming partly cloudy. Lows in the upper 50s. Northwest Winds around 5 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

    68.7 °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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