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

31°F

-1°C

Humidity 67%
Wind Speed NE 7 mph
Barometer 29.96 in (1014.4 mb)
Dewpoint 21°F (-6°C)
Visibility 10.00 mi
Wind Chill24°F (-4°C)
Last update 27 Feb 12:56 am EST
Extended Forecast for

Port Jefferson NY

  • Overnight

    Overnight: Mostly clear, with a low around 25. North wind 3 to 5 mph.

    Low: 25 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 41. Calm wind becoming south around 5 mph.

    High: 41 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 28. Light south wind.

    Low: 28 °F

    Mostly Clear

  • Saturday

    Saturday: Mostly sunny, with a high near 47. Southwest wind 3 to 6 mph.

    High: 47 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 29. Calm wind becoming north around 5 mph after midnight.

    Low: 29 °F

    Partly Cloudy

  • Sunday

    Sunday: Scattered snow showers before 1pm. Cloudy, then gradual clearing during the afternoon, with a high near 36. Chance of precipitation is 40%.

    High: 36 °F

    Scattered
    Snow Showers

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 16.

    Low: 16 °F

    Partly Cloudy

  • Monday

    Monday: Mostly cloudy, with a high near 27.

    High: 27 °F

    Mostly Cloudy

  • Monday Night

    Monday Night: Mostly cloudy, with a low around 19.

    Low: 19 °F

    Mostly Cloudy

Detailed Forecast

Overnight
Mostly clear, with a low around 25. North wind 3 to 5 mph.
Friday
Sunny, with a high near 41. Calm wind becoming south around 5 mph.
Friday Night
Mostly clear, with a low around 28. Light south wind.
Saturday
Mostly sunny, with a high near 47. Southwest wind 3 to 6 mph.
Saturday Night
Partly cloudy, with a low around 29. Calm wind becoming north around 5 mph after midnight.
Sunday
Scattered snow showers before 1pm. Cloudy, then gradual clearing during the afternoon, with a high near 36. Chance of precipitation is 40%.
Sunday Night
Partly cloudy, with a low around 16.
Monday
Mostly cloudy, with a high near 27.
Monday Night
Mostly cloudy, with a low around 19.
Tuesday
A chance of rain and snow after 1pm. Mostly cloudy, with a high near 36. Chance of precipitation is 30%.
Tuesday Night
Rain likely. Cloudy, with a low around 30. Chance of precipitation is 70%.
Wednesday
A 30 percent chance of rain. Partly sunny, with a high near 42.
Wednesday Night
Mostly cloudy, with a low around 32.
Thursday
A 30 percent chance of rain. Mostly cloudy, with a high near 44.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.93°N 73.06°W (Elev. 161 ft)
Last Update:
12:50 am EST Feb 27, 2026
Forecast Valid:
1am EST Feb 27, 2026-6pm EST Mar 5, 2026
 
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