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

27°F

-3°C

Humidity 45%
Wind Speed NW 13 G 20 mph
Barometer 29.81 in (1009.5 mb)
Dewpoint 8°F (-13°C)
Visibility 10.00 mi
Wind Chill16°F (-9°C)
Last update 2 Jan 7:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Mostly clear, with a low around 23. Wind chill values between 15 and 20. Breezy, with a west wind 17 to 20 mph.

    Low: 23 °F

    Partly Cloudy
    and Breezy
    then Mostly
    Clear

  • Saturday

    Saturday: Increasing clouds, with a high near 30. Wind chill values between 15 and 20. West wind 10 to 16 mph.

    High: 30 °F

    Increasing
    Clouds

  • Saturday Night

    Saturday Night: A slight chance of snow showers between 10pm and 1am, then a chance of light snow after 1am. Cloudy, with a steady temperature around 30. Wind chill values between 20 and 25. West wind 5 to 8 mph. Chance of precipitation is 50%.

    Low: 30 °F

    Slight Chance
    Snow Showers
    then Chance
    Light Snow

  • Sunday

    Sunday: A 20 percent chance of light snow before 10am. Cloudy, then gradually becoming mostly sunny, with a high near 33. Wind chill values between 20 and 25. Northwest wind 8 to 17 mph.

    High: 33 °F

    Slight Chance
    Light Snow
    then Partly
    Sunny

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 20. Blustery, with a northwest wind 13 to 21 mph.

    Low: 20 °F

    Partly Cloudy
    and Blustery
    then Partly
    Cloudy

  • Monday

    Monday: Increasing clouds, with a high near 32.

    High: 32 °F

    Increasing
    Clouds

  • Monday Night

    Monday Night: Cloudy, with a low around 27.

    Low: 27 °F

    Cloudy

  • Tuesday

    Tuesday: Mostly cloudy, with a high near 41.

    High: 41 °F

    Mostly Cloudy

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 36.

    Low: 36 °F

    Mostly Cloudy

Detailed Forecast

Tonight
Mostly clear, with a low around 23. Wind chill values between 15 and 20. Breezy, with a west wind 17 to 20 mph.
Saturday
Increasing clouds, with a high near 30. Wind chill values between 15 and 20. West wind 10 to 16 mph.
Saturday Night
A slight chance of snow showers between 10pm and 1am, then a chance of light snow after 1am. Cloudy, with a steady temperature around 30. Wind chill values between 20 and 25. West wind 5 to 8 mph. Chance of precipitation is 50%.
Sunday
A 20 percent chance of light snow before 10am. Cloudy, then gradually becoming mostly sunny, with a high near 33. Wind chill values between 20 and 25. Northwest wind 8 to 17 mph.
Sunday Night
Partly cloudy, with a low around 20. Blustery, with a northwest wind 13 to 21 mph.
Monday
Increasing clouds, with a high near 32.
Monday Night
Cloudy, with a low around 27.
Tuesday
Mostly cloudy, with a high near 41.
Tuesday Night
Mostly cloudy, with a low around 36.
Wednesday
Mostly cloudy, with a high near 43.
Wednesday Night
Partly cloudy, with a low around 35.
Thursday
Mostly sunny, with a high near 44.
Thursday Night
Mostly cloudy, with a low around 38.
Friday
A 30 percent chance of rain. Mostly cloudy, with a high near 46.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.96°N 73.08°W (Elev. 3 ft)
Last Update:
3:52 pm EST Jan 2, 2026
Forecast Valid:
8pm EST Jan 2, 2026-6pm EST Jan 9, 2026
 
Forecast Discussion
 
Get as KML Get as XML

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