National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Hazardous Weather Conditions

Current conditions at

Islip, Long Island Mac Arthur Airport (KISP)

Lat: 40.79°NLon: 73.1°WElev: 98ft.

A Few Clouds

14°F

-10°C

Humidity 56%
Wind Speed NW 12 mph
Barometer 30.07 in (1018.3 mb)
Dewpoint 1°F (-17°C)
Visibility 10.00 mi
Wind Chill0°F (-18°C)
Last update 29 Jan 8:56 am EST
Extended Forecast for

Port Jefferson NY

Cold Weather Advisory January 30, 12:00am until January 30, 10:00am
Click here for hazard details and duration
Cold Weather Advisory

  • Today

    Today: Mostly sunny, with a high near 22. Wind chill values between zero and 10. West wind 11 to 15 mph.

    High: 22 °F

    Mostly Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 10. Wind chill values between -5 and 5. Breezy, with a northwest wind around 21 mph.

    Low: 10 °F

    Mostly Clear
    and Breezy

  • Friday

    Friday: Sunny and cold, with a high near 18. Wind chill values between -5 and zero. West wind around 17 mph.

    High: 18 °F

    Cold

  • Friday Night

    Friday Night: Mostly clear, with a low around 8. Wind chill values between -5 and zero. Northwest wind 10 to 17 mph.

    Low: 8 °F

    Mostly Clear

  • Saturday

    Saturday: Mostly sunny and cold, with a high near 20. North wind around 10 mph.

    High: 20 °F

    Cold

  • Saturday Night

    Saturday Night: A 30 percent chance of snow after 1am. Mostly cloudy, with a low around 16. Windy.

    Low: 16 °F

    Mostly Cloudy
    and Blustery
    then Chance
    Snow and
    Windy

  • Sunday

    Sunday: A 50 percent chance of snow. Cloudy, with a high near 25. Windy.

    High: 25 °F

    Chance Snow
    and Windy

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 20. Windy.

    Low: 20 °F

    Mostly Cloudy
    and Windy

  • Monday

    Monday: Mostly sunny, with a high near 31. Blustery.

    High: 31 °F

    Partly Sunny
    and Blustery
    then Mostly
    Sunny

Detailed Forecast

Today
Mostly sunny, with a high near 22. Wind chill values between zero and 10. West wind 11 to 15 mph.
Tonight
Mostly clear, with a low around 10. Wind chill values between -5 and 5. Breezy, with a northwest wind around 21 mph.
Friday
Sunny and cold, with a high near 18. Wind chill values between -5 and zero. West wind around 17 mph.
Friday Night
Mostly clear, with a low around 8. Wind chill values between -5 and zero. Northwest wind 10 to 17 mph.
Saturday
Mostly sunny and cold, with a high near 20. North wind around 10 mph.
Saturday Night
A 30 percent chance of snow after 1am. Mostly cloudy, with a low around 16. Windy.
Sunday
A 50 percent chance of snow. Cloudy, with a high near 25. Windy.
Sunday Night
Mostly cloudy, with a low around 20. Windy.
Monday
Mostly sunny, with a high near 31. Blustery.
Monday Night
Mostly clear, with a low around 21.
Tuesday
Mostly sunny, with a high near 32.
Tuesday Night
Partly cloudy, with a low around 22.
Wednesday
Mostly sunny, with a high near 30.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.96°N 73.08°W (Elev. 3 ft)
Last Update:
1:43 am EST Jan 29, 2026
Forecast Valid:
9am EST Jan 29, 2026-6pm EST Feb 4, 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