Port Jefferson Harbor Entrance Weather Forecast

    • 70
    • 80

    Chance Rain Showers

    • 66
    • 77

    Partly Sunny

    • 64
    • 72

    Mostly Sunny

    • 67
    • 75

    Mostly Sunny

    • 67
    • 76

    Partly Sunny

    • 70
    • 74

    Mostly Cloudy

Today 4 Sep Northwest Suffolk

Partly sunny. A chance of Showers with a slight chance of Thunderstorms this morning. Highs in the lower 80s. Northwest Winds 5 to 10 Mph. Chance of rain 30 percent.

Tonight 4 Sep Northwest Suffolk

Partly cloudy in the Evening, then clearing. Lows in the mid 60s. Northwest Winds 5 to 10 Mph.

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Port Jefferson Harbor Entrance Temperature Statistics

September Temperature

Islip, Long Island Mac Arthur Airport (11.8 miles)

  • Lowest 2 September, 2026

    64.9 °F

  • Average September

    70.8 °F

  • Highest 1 September, 2026

    78.7 °F

Climate (2021–2026)

Islip, Long Island Mac Arthur Airport (11.8 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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