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.

Fair

34°F

1°C

Humidity 73%
Wind Speed W 5 mph
Barometer 29.94 in (1014.0 mb)
Dewpoint 26°F (-3°C)
Visibility 10.00 mi
Wind Chill29°F (-2°C)
Last update 6 Dec 9:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Mostly clear, with a low around 31. Northwest wind 6 to 9 mph.

    Low: 31 °F

    Mostly Clear

  • Sunday

    Sunday: Partly sunny, with a high near 41. North wind around 6 mph becoming south in the afternoon.

    High: 41 °F

    Partly Sunny

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 25. Wind chill values between 15 and 20. Southwest wind 7 to 15 mph becoming northwest after midnight.

    Low: 25 °F

    Partly Cloudy

  • Monday

    Monday: Mostly sunny, with a high near 31. Wind chill values between 15 and 20. North wind 14 to 17 mph.

    High: 31 °F

    Mostly Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 19. North wind 6 to 13 mph.

    Low: 19 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Increasing clouds, with a high near 39.

    High: 39 °F

    Increasing
    Clouds

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 33.

    Low: 33 °F

    Mostly Cloudy

  • Wednesday

    Wednesday: A 40 percent chance of rain. Mostly cloudy, with a high near 47.

    High: 47 °F

    Chance Rain

  • Wednesday Night

    Wednesday Night: A 40 percent chance of rain. Mostly cloudy, with a low around 36.

    Low: 36 °F

    Chance Rain

Detailed Forecast

Tonight
Mostly clear, with a low around 31. Northwest wind 6 to 9 mph.
Sunday
Partly sunny, with a high near 41. North wind around 6 mph becoming south in the afternoon.
Sunday Night
Partly cloudy, with a low around 25. Wind chill values between 15 and 20. Southwest wind 7 to 15 mph becoming northwest after midnight.
Monday
Mostly sunny, with a high near 31. Wind chill values between 15 and 20. North wind 14 to 17 mph.
Monday Night
Partly cloudy, with a low around 19. North wind 6 to 13 mph.
Tuesday
Increasing clouds, with a high near 39.
Tuesday Night
Mostly cloudy, with a low around 33.
Wednesday
A 40 percent chance of rain. Mostly cloudy, with a high near 47.
Wednesday Night
A 40 percent chance of rain. Mostly cloudy, with a low around 36.
Thursday
A 30 percent chance of rain before 1pm. Partly sunny, with a high near 43.
Thursday Night
A 40 percent chance of rain. Mostly cloudy, with a low around 31.
Friday
A 30 percent chance of rain. Partly sunny, with a high near 40.
Friday Night
A 30 percent chance of snow. Partly cloudy, with a low around 25.
Saturday
Mostly sunny, with a high near 34.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.95°N 73.05°W (Elev. 151 ft)
Last Update:
4:40 pm EST Dec 6, 2025
Forecast Valid:
10pm EST Dec 6, 2025-6pm EST Dec 13, 2025
 
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