Port Jefferson Weather Forecast

    • 66
    • 74

    Partly Sunny

    • 66
    • 77

    Partly Sunny

    • 65
    • 75

    Partly Sunny

    • 60
    • 77

    Partly Sunny

    • 61
    • 76

    Partly Sunny

    • 62
    • 75

    Partly Sunny

Today 13 Sep Northwest Suffolk

Sunny. Highs in the mid 70s. South Winds 5 to 10 Mph.

Tonight 13 Sep Northwest Suffolk

Partly cloudy. Lows in the lower 60s. South Winds 5 to 10 Mph.

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Port Jefferson Temperature Statistics

September Temperature

Islip, Long Island Mac Arthur Airport (10.6 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 (10.6 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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