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.

Light Snow Fog/Mist

32°F

0°C

Humidity 96%
Wind Speed NW 7 mph
Barometer 29.82 in (1009.7 mb)
Dewpoint 31°F (-1°C)
Visibility 1.00 mi
Wind Chill25°F (-4°C)
Last update 18 Jan 7:56 pm EST
Extended Forecast for

Port Jefferson NY

Winter Weather Advisory January 18, 08:48pm until January 19, 04:00am
Click here for hazard details and duration
Winter Weather Advisory
  •  
    Winter Weather Advisory January 18, 08:48pm until January 19, 04:00am

    NOW until 4:00am Mon

    Winter Weather Advisory

  • Tonight

    Low: 25 °F

    Snow then
    Snow Likely

  • M.L.King Day

    M.L.King Day: Mostly cloudy, then gradually becoming sunny, with a high near 32. Wind chill values between 15 and 20. West wind 11 to 17 mph.

    High: 32 °F

    Decreasing
    Clouds

  • Monday Night

    Monday Night: Mostly cloudy, then gradually becoming clear, with a low around 19. Wind chill values between 5 and 15. Breezy, with a west wind 17 to 25 mph.

    Low: 19 °F

    Decreasing
    Clouds and
    Breezy

  • Tuesday

    Tuesday: Sunny, with a high near 24. Wind chill values between 5 and 10. Breezy, with a west wind around 21 mph.

    High: 24 °F

    Sunny and
    Breezy

  • Tuesday Night

    Tuesday Night: Clear, with a low around 16. West wind 10 to 16 mph.

    Low: 16 °F

    Clear

  • Wednesday

    Wednesday: Increasing clouds, with a high near 36.

    High: 36 °F

    Increasing
    Clouds

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 32.

    Low: 32 °F

    Mostly Cloudy

  • Thursday

    Thursday: A 30 percent chance of rain before 1pm. Partly sunny, with a high near 38.

    High: 38 °F

    Chance Rain

Detailed Forecast

Tonight
Snow, mainly before 1am. Low around 25. Northwest wind 6 to 10 mph. Chance of precipitation is 100%. Total nighttime snow accumulation of 2 to 4 inches possible.
M.L.King Day
Mostly cloudy, then gradually becoming sunny, with a high near 32. Wind chill values between 15 and 20. West wind 11 to 17 mph.
Monday Night
Mostly cloudy, then gradually becoming clear, with a low around 19. Wind chill values between 5 and 15. Breezy, with a west wind 17 to 25 mph.
Tuesday
Sunny, with a high near 24. Wind chill values between 5 and 10. Breezy, with a west wind around 21 mph.
Tuesday Night
Clear, with a low around 16. West wind 10 to 16 mph.
Wednesday
Increasing clouds, with a high near 36.
Wednesday Night
Mostly cloudy, with a low around 32.
Thursday
A 30 percent chance of rain before 1pm. Partly sunny, with a high near 38.
Thursday Night
Mostly clear, with a low around 23. Breezy.
Friday
Mostly sunny, with a high near 30.
Friday Night
Mostly cloudy, with a low around 22.
Saturday
A 30 percent chance of snow. Partly sunny, with a high near 29.
Saturday Night
A 30 percent chance of snow. Mostly cloudy, with a low around 16.
Sunday
A 30 percent chance of snow. Partly sunny, with a high near 23.
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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:
8:25 pm EST Jan 18, 2026
Forecast Valid:
8pm EST Jan 18, 2026-6pm EST Jan 25, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

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Hourly Weather Forecast

National Digital Forecast Database

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation