Great South Bay Weather Forecast

    • 63
    • 75

    Partly Sunny

    • 65
    • 74

    Partly Sunny

    • 59
    • 74

    Partly Sunny

    • 60
    • 72

    Chance Rain Showers

    • 61
    • 73

    Slight Chance Rain Showers

    • 59
    • 76

    Partly Sunny

Today 14 Sep Southwest Suffolk

Partly sunny. A slight chance of Showers in the afternoon. Highs in the upper 70s. Southwest Winds 5 to 10 Mph. Chance of rain 20 percent.

Tonight 14 Sep Southwest Suffolk

Partly cloudy with a slight chance of Showers in the Evening, then mostly clear after midnight. Patchy fog after midnight. Lows in the lower 60s. South Winds around 5 Mph. Chance of rain 20 percent.

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Great South Bay Temperature Statistics

September Temperature

Islip, Long Island Mac Arthur Airport (8.1 miles)

  • Lowest 9 September, 2025

    54 °F

  • Average September

    68.8 °F

  • Highest 6 September, 2025

    81 °F

Climate (2020–Present)

Islip, Long Island Mac Arthur Airport (8.1 miles)

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  • Average Low 2020–2025

    47.4 °F

  • Average 2020–2025

    55.2 °F

  • Average High 2020–2025

    63.1 °F
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