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

33°F

1°C

Humidity 96%
Wind Speed NE 8 mph
Barometer 29.91 in (1012.7 mb)
Dewpoint 32°F (0°C)
Visibility 1.00 mi
Wind Chill26°F (-3°C)
Last update 18 Jan 1:56 pm EST
Extended Forecast for

Port Jefferson NY

Winter Weather Advisory January 18, 02:25pm until January 19, 04:00am
Click here for hazard details and duration
Winter Weather Advisory
  •  
    Winter Weather Advisory January 18, 02:25pm until January 19, 04:00am

    NOW until 4:00am Mon

    Winter Weather Advisory

  • This Afternoon

    High: 34 °F

    Rain/Snow

  • Tonight

    Tonight: Snow, mainly before 10pm. Low around 25. Wind chill values between 15 and 20. Northeast wind 8 to 13 mph becoming west after midnight. Chance of precipitation is 80%. New snow accumulation of 1 to 3 inches possible.

    Low: 25 °F

    Snow then
    Chance Snow

  • M.L.King Day

    M.L.King Day: Mostly sunny, with a high near 32. Wind chill values between 10 and 15. Breezy, with a west wind 13 to 18 mph increasing to 20 to 25 mph in the afternoon.

    High: 32 °F

    Mostly Sunny
    and Breezy

  • Monday Night

    Monday Night: Partly cloudy, with a low around 20. Wind chill values between 10 and 15. Breezy, with a west wind 22 to 25 mph.

    Low: 20 °F

    Partly Cloudy
    and Breezy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 24. Breezy, with a west wind 20 to 25 mph.

    High: 24 °F

    Mostly Sunny
    and Breezy

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 17.

    Low: 17 °F

    Mostly Clear

  • Wednesday

    Wednesday: Mostly sunny, with a high near 37.

    High: 37 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 31.

    Low: 31 °F

    Mostly Cloudy

Detailed Forecast

This Afternoon
Snow, possibly mixed with rain, becoming all snow after 4pm. High near 34. Northeast wind around 8 mph. Chance of precipitation is 100%. Total daytime snow accumulation of less than a half inch possible.
Tonight
Snow, mainly before 10pm. Low around 25. Wind chill values between 15 and 20. Northeast wind 8 to 13 mph becoming west after midnight. Chance of precipitation is 80%. New snow accumulation of 1 to 3 inches possible.
M.L.King Day
Mostly sunny, with a high near 32. Wind chill values between 10 and 15. Breezy, with a west wind 13 to 18 mph increasing to 20 to 25 mph in the afternoon.
Monday Night
Partly cloudy, with a low around 20. Wind chill values between 10 and 15. Breezy, with a west wind 22 to 25 mph.
Tuesday
Mostly sunny, with a high near 24. Breezy, with a west wind 20 to 25 mph.
Tuesday Night
Mostly clear, with a low around 17.
Wednesday
Mostly sunny, with a high near 37.
Wednesday Night
Mostly cloudy, with a low around 31.
Thursday
Partly sunny, with a high near 36.
Thursday Night
Partly cloudy, with a low around 24.
Friday
Mostly sunny, with a high near 33.
Friday Night
Mostly cloudy, with a low around 28.
Saturday
A chance of rain and snow. Mostly cloudy, with a high near 35. Chance of precipitation is 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:
10:00 am EST Jan 18, 2026
Forecast Valid:
2pm EST Jan 18, 2026-6pm EST Jan 24, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

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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