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

48°F

9°C

Humidity 80%
Wind Speed SW 5 mph
Barometer 30.07 in (1018.3 mb)
Dewpoint 42°F (6°C)
Visibility 10.00 mi
Wind Chill46°F (8°C)
Last update 21 Nov 9:56 am EST
Extended Forecast for

Port Jefferson NY

  • Today

    Today: A chance of sprinkles before 1pm. Cloudy, with a high near 52. Southwest wind 7 to 9 mph.

    High: 52 °F

    Chance
    Sprinkles

  • Tonight

    Tonight: Rain likely after 1am. Cloudy, with a low around 44. Southwest wind around 6 mph becoming northwest after midnight. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

    Low: 44 °F

    Cloudy then
    Rain Likely

  • Saturday

    Saturday: A 30 percent chance of rain, mainly before 10am. Cloudy, then gradually becoming mostly sunny, with a high near 50. North wind 8 to 10 mph.

    High: 50 °F

    Chance Rain

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 35. North wind 7 to 10 mph.

    Low: 35 °F

    Partly Cloudy

  • Sunday

    Sunday: Mostly sunny, with a high near 48. West wind 6 to 9 mph.

    High: 48 °F

    Mostly Sunny

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 40.

    Low: 40 °F

    Partly Cloudy

  • Monday

    Monday: Sunny, with a high near 51.

    High: 51 °F

    Sunny

  • Monday Night

    Monday Night: Mostly cloudy, with a low around 42.

    Low: 42 °F

    Mostly Cloudy

  • Tuesday

    Tuesday: A 30 percent chance of rain after 1pm. Cloudy, with a high near 55.

    High: 55 °F

    Mostly Cloudy
    then Chance
    Rain

Detailed Forecast

Today
A chance of sprinkles before 1pm. Cloudy, with a high near 52. Southwest wind 7 to 9 mph.
Tonight
Rain likely after 1am. Cloudy, with a low around 44. Southwest wind around 6 mph becoming northwest after midnight. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Saturday
A 30 percent chance of rain, mainly before 10am. Cloudy, then gradually becoming mostly sunny, with a high near 50. North wind 8 to 10 mph.
Saturday Night
Partly cloudy, with a low around 35. North wind 7 to 10 mph.
Sunday
Mostly sunny, with a high near 48. West wind 6 to 9 mph.
Sunday Night
Partly cloudy, with a low around 40.
Monday
Sunny, with a high near 51.
Monday Night
Mostly cloudy, with a low around 42.
Tuesday
A 30 percent chance of rain after 1pm. Cloudy, with a high near 55.
Tuesday Night
Rain likely. Cloudy, with a low around 50. Chance of precipitation is 70%.
Wednesday
A 50 percent chance of rain. Mostly cloudy, with a high near 58.
Wednesday Night
A 40 percent chance of rain. Mostly cloudy, with a low around 44.
Thanksgiving Day
Partly sunny, with a high near 52.
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:
10:11 am EST Nov 21, 2025
Forecast Valid:
10am EST Nov 21, 2025-6pm EST Nov 27, 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