National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce
Current conditions at

Islip, Long Island Mac Arthur Airport (KISP)

Lat: 40.79°NLon: 73.1°WElev: 98ft.

A Few Clouds

26°F

-3°C

Humidity 42%
Wind Speed W 12 mph
Barometer 29.52 in (999.6 mb)
Dewpoint 6°F (-14°C)
Visibility 10.00 mi
Wind Chill15°F (-9°C)
Last update 15 Jan 10:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Partly cloudy, with a low around 24. Wind chill values between 10 and 15. Windy, with a west wind 26 to 31 mph.

    Low: 24 °F

    Partly Cloudy
    and Windy

  • Friday

    Friday: Sunny, with a high near 35. Wind chill values between 5 and 15. Windy, with a west wind 26 to 31 mph decreasing to 16 to 21 mph in the afternoon.

    High: 35 °F

    Sunny and
    Windy

  • Friday Night

    Friday Night: A 20 percent chance of snow after 1am. Increasing clouds, with a temperature rising to around 36 by 2am. Wind chill values between 25 and 30. Southwest wind 9 to 14 mph.

    Low: 33 °F⇑

    Mostly Cloudy
    then Slight
    Chance Snow

  • Saturday

    Saturday: A chance of snow before 10am, then a chance of rain and snow between 10am and 4pm, then a chance of rain after 4pm. Cloudy, with a high near 40. Southwest wind 8 to 10 mph. Chance of precipitation is 50%.

    High: 40 °F

    Chance
    Rain/Snow

  • Saturday Night

    Saturday Night: Mostly cloudy, with a low around 33. West wind around 10 mph.

    Low: 33 °F

    Mostly Cloudy

  • Sunday

    Sunday: A 30 percent chance of snow after 1pm. Mostly cloudy, with a high near 36.

    High: 36 °F

    Mostly Cloudy
    then Chance
    Snow

  • Sunday Night

    Sunday Night: Mostly cloudy, then gradually becoming mostly clear, with a low around 25.

    Low: 25 °F

    Decreasing
    Clouds

  • M.L.King Day

    M.L.King Day: Sunny, with a high near 32. Breezy.

    High: 32 °F

    Sunny then
    Sunny and
    Breezy

  • Monday Night

    Monday Night: Mostly clear, with a low around 18. Breezy.

    Low: 18 °F

    Mostly Clear
    and Breezy

Detailed Forecast

Tonight
Partly cloudy, with a low around 24. Wind chill values between 10 and 15. Windy, with a west wind 26 to 31 mph.
Friday
Sunny, with a high near 35. Wind chill values between 5 and 15. Windy, with a west wind 26 to 31 mph decreasing to 16 to 21 mph in the afternoon.
Friday Night
A 20 percent chance of snow after 1am. Increasing clouds, with a temperature rising to around 36 by 2am. Wind chill values between 25 and 30. Southwest wind 9 to 14 mph.
Saturday
A chance of snow before 10am, then a chance of rain and snow between 10am and 4pm, then a chance of rain after 4pm. Cloudy, with a high near 40. Southwest wind 8 to 10 mph. Chance of precipitation is 50%.
Saturday Night
Mostly cloudy, with a low around 33. West wind around 10 mph.
Sunday
A 30 percent chance of snow after 1pm. Mostly cloudy, with a high near 36.
Sunday Night
Mostly cloudy, then gradually becoming mostly clear, with a low around 25.
M.L.King Day
Sunny, with a high near 32. Breezy.
Monday Night
Mostly clear, with a low around 18. Breezy.
Tuesday
Mostly sunny, with a high near 23. Breezy.
Tuesday Night
Mostly clear, with a low around 17. Breezy.
Wednesday
Mostly sunny, with a high near 30.
Wednesday Night
Mostly cloudy, with a low around 27.
Thursday
Mostly sunny, with a high near 34.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.96°N 73.08°W (Elev. 3 ft)
Last Update:
12:42 pm EST Jan 15, 2026
Forecast Valid:
11pm EST Jan 15, 2026-6pm EST Jan 22, 2026
 
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Additional Resources

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Hourly Weather Forecast

National Digital Forecast Database

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation