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.

Partly Cloudy

37°F

3°C

Humidity 79%
Wind Speed W 6 mph
Barometer 29.73 in (1006.7 mb)
Dewpoint 31°F (-1°C)
Visibility 10.00 mi
Wind Chill32°F (0°C)
Last update 26 Feb 12:56 am EST
Extended Forecast for

Port Jefferson NY

  • Overnight

    Overnight: Partly cloudy, with a low around 33. West wind around 14 mph.

    Low: 33 °F

    Partly Cloudy

  • Thursday

    Thursday: A 20 percent chance of snow after 1pm. Increasing clouds, with a high near 36. West wind 6 to 10 mph.

    High: 36 °F

    Mostly Sunny
    then Slight
    Chance Snow

  • Thursday Night

    Thursday Night: Mostly cloudy, then gradually becoming mostly clear, with a low around 24. North wind around 6 mph.

    Low: 24 °F

    Decreasing
    Clouds

  • Friday

    Friday: Sunny, with a high near 36. Wind chill values between 20 and 30. Calm wind becoming south around 6 mph in the afternoon.

    High: 36 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 32. South wind around 7 mph.

    Low: 32 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 42.

    High: 42 °F

    Sunny

  • Saturday Night

    Saturday Night: Increasing clouds, with a low around 31.

    Low: 31 °F

    Increasing
    Clouds

  • Sunday

    Sunday: Mostly cloudy, with a high near 35.

    High: 35 °F

    Mostly Cloudy

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 20. Blustery.

    Low: 20 °F

    Mostly Clear
    and Blustery
    then Partly
    Cloudy

Detailed Forecast

Overnight
Partly cloudy, with a low around 33. West wind around 14 mph.
Thursday
A 20 percent chance of snow after 1pm. Increasing clouds, with a high near 36. West wind 6 to 10 mph.
Thursday Night
Mostly cloudy, then gradually becoming mostly clear, with a low around 24. North wind around 6 mph.
Friday
Sunny, with a high near 36. Wind chill values between 20 and 30. Calm wind becoming south around 6 mph in the afternoon.
Friday Night
Mostly clear, with a low around 32. South wind around 7 mph.
Saturday
Sunny, with a high near 42.
Saturday Night
Increasing clouds, with a low around 31.
Sunday
Mostly cloudy, with a high near 35.
Sunday Night
Partly cloudy, with a low around 20. Blustery.
Monday
A 30 percent chance of snow. Mostly cloudy, with a high near 26.
Monday Night
Mostly cloudy, with a low around 22.
Tuesday
Mostly cloudy, with a high near 34.
Tuesday Night
A 50 percent chance of rain. Cloudy, with a low around 31.
Wednesday
A 50 percent chance of rain. Mostly sunny, with a high near 40.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.96°N 73.08°W (Elev. 3 ft)
Last Update:
12:57 am EST Feb 26, 2026
Forecast Valid:
1am EST Feb 26, 2026-6pm EST Mar 4, 2026
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

Hourly Weather Forecast

National Digital Forecast Database

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation