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.

Overcast

43°F

6°C

Humidity 80%
Wind Speed NW 6 mph
Barometer 29.91 in (1012.8 mb)
Dewpoint 37°F (3°C)
Visibility 10.00 mi
Wind Chill39°F (4°C)
Last update 6 Dec 10:56 am EST
Extended Forecast for

Port Jefferson NY

  • Today

    Today: A slight chance of drizzle before 1pm. Mostly cloudy, with a high near 41. West wind around 7 mph.

    High: 41 °F

    Slight Chance
    Drizzle

  • Tonight

    Tonight: Partly cloudy, with a low around 31. West wind 6 to 9 mph.

    Low: 31 °F

    Partly Cloudy

  • Sunday

    Sunday: Partly sunny, with a high near 40. North wind around 6 mph becoming southwest in the afternoon.

    High: 40 °F

    Partly Sunny

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 26. Wind chill values between 15 and 20. Southwest wind 6 to 11 mph becoming northwest 13 to 18 mph after midnight.

    Low: 26 °F

    Mostly Cloudy

  • Monday

    Monday: Mostly sunny, with a high near 32. Breezy, with a north wind 14 to 20 mph.

    High: 32 °F

    Mostly Sunny
    and Breezy
    then Mostly
    Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 20.

    Low: 20 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Partly sunny, with a high near 39.

    High: 39 °F

    Partly Sunny

  • Tuesday Night

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

    Low: 33 °F

    Mostly Cloudy

  • Wednesday

    Wednesday: A 30 percent chance of rain after 1pm. Mostly cloudy, with a high near 47.

    High: 47 °F

    Mostly Cloudy
    then Chance
    Rain

Detailed Forecast

Today
A slight chance of drizzle before 1pm. Mostly cloudy, with a high near 41. West wind around 7 mph.
Tonight
Partly cloudy, with a low around 31. West wind 6 to 9 mph.
Sunday
Partly sunny, with a high near 40. North wind around 6 mph becoming southwest in the afternoon.
Sunday Night
Mostly cloudy, with a low around 26. Wind chill values between 15 and 20. Southwest wind 6 to 11 mph becoming northwest 13 to 18 mph after midnight.
Monday
Mostly sunny, with a high near 32. Breezy, with a north wind 14 to 20 mph.
Monday Night
Partly cloudy, with a low around 20.
Tuesday
Partly sunny, with a high near 39.
Tuesday Night
Mostly cloudy, with a low around 33.
Wednesday
A 30 percent chance of rain after 1pm. Mostly cloudy, with a high near 47.
Wednesday Night
A 50 percent chance of rain. Mostly cloudy, with a low around 36.
Thursday
A 30 percent chance of rain. Partly sunny, with a high near 42.
Thursday Night
A 30 percent chance of rain. Mostly cloudy, with a low around 29.
Friday
A chance of rain and snow. Partly sunny, with a high near 37. Chance of precipitation is 30%.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.95°N 73.05°W (Elev. 151 ft)
Last Update:
7:42 am EST Dec 6, 2025
Forecast Valid:
11am EST Dec 6, 2025-6pm EST Dec 12, 2025
 
Forecast Discussion
 
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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