Great South Bay Weather Forecast

    • 59
    • 65

    Rain

    • 62
    • 68

    Partly Sunny

    • 64
    • 70

    Partly Sunny

    • 67
    • 71

    Partly Sunny

    • 61
    • 72

    Slight Chance Rain Showers

    • 59
    • 66

    Mostly Cloudy

Today 28 Sep Southwest Suffolk

Rain. Highs in the mid 60s. Northeast Winds 15 to 20 Mph. Chance of rain near 100 percent.

Tonight 28 Sep Southwest Suffolk

Mostly cloudy. A chance of rain in the evening. Lows in the upper 50s. North Winds 10 to 15 Mph. Chance of rain 40 percent.

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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

    69 °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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