Port Jefferson Weather Forecast

    • 36
    • 41

    Increasing Clouds

    • 30
    • 44

    Partly Sunny

    • 33
    • 37

    Partly Sunny

    • 36
    • 43

    Chance Rain/Snow

    • 34
    • 41

    Partly Sunny

    • 39
    • 43

    Chance Rain

    • 37
    • 47

    Slight Chance Rain

Today 20 Dec Northwest Suffolk

Partly sunny. Cooler with Highs in the lower 40s. Southwest Winds 5 to 10 Mph.

Tonight 20 Dec Northwest Suffolk

Mostly cloudy. Lows in the lower 30s. Southwest Winds 10 to 15 Mph with Gusts up to 25 Mph.

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Port Jefferson Temperature Statistics

December Temperature

Islip, Long Island Mac Arthur Airport (10.6 miles)

  • Lowest 15 December, 2025

    19.9 °F

  • Average December

    34.3 °F

  • Highest 18 December, 2025

    51.1 °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

    55.3 °F

  • Average High 2020–2025

    63.1 °F
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