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.

Partly Cloudy

40°F

4°C

Humidity 45%
Wind Speed NW 13 G 24 mph
Barometer 30.04 in (1017.2 mb)
Dewpoint 20°F (-7°C)
Visibility 10.00 mi
Wind Chill32°F (0°C)
Last update 4 Dec 4:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Mostly clear, with a low around 19. Wind chill values between 10 and 15. Blustery, with a north wind 17 to 22 mph decreasing to 8 to 13 mph after midnight.

    Low: 19 °F

    Mostly Clear
    and Blustery
    then Partly
    Cloudy

  • Friday

    Friday: Increasing clouds, with a high near 35. Wind chill values between 10 and 20. Northeast wind around 6 mph becoming south in the afternoon.

    High: 35 °F

    Increasing
    Clouds

  • Friday Night

    Friday Night: A slight chance of snow before 10pm, then a slight chance of rain and snow between 10pm and 1am, then a chance of rain after 1am. Mostly cloudy, with a temperature rising to around 34 by 3am. Light and variable wind. Chance of precipitation is 40%.

    Low: 31 °F⇑

    Chance
    Rain/Snow

  • Saturday

    Saturday: A 20 percent chance of rain before 1pm. Mostly cloudy, with a high near 42. West wind 3 to 8 mph.

    High: 42 °F

    Slight Chance
    Rain

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 31. West wind around 8 mph.

    Low: 31 °F

    Partly Cloudy

  • Sunday

    Sunday: Partly sunny, with a high near 41.

    High: 41 °F

    Partly Sunny

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 27.

    Low: 27 °F

    Mostly Cloudy

  • Monday

    Monday: Mostly sunny, with a high near 35.

    High: 35 °F

    Mostly Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 20.

    Low: 20 °F

    Mostly Clear

Detailed Forecast

Tonight
Mostly clear, with a low around 19. Wind chill values between 10 and 15. Blustery, with a north wind 17 to 22 mph decreasing to 8 to 13 mph after midnight.
Friday
Increasing clouds, with a high near 35. Wind chill values between 10 and 20. Northeast wind around 6 mph becoming south in the afternoon.
Friday Night
A slight chance of snow before 10pm, then a slight chance of rain and snow between 10pm and 1am, then a chance of rain after 1am. Mostly cloudy, with a temperature rising to around 34 by 3am. Light and variable wind. Chance of precipitation is 40%.
Saturday
A 20 percent chance of rain before 1pm. Mostly cloudy, with a high near 42. West wind 3 to 8 mph.
Saturday Night
Partly cloudy, with a low around 31. West wind around 8 mph.
Sunday
Partly sunny, with a high near 41.
Sunday Night
Mostly cloudy, with a low around 27.
Monday
Mostly sunny, with a high near 35.
Monday Night
Mostly clear, with a low around 20.
Tuesday
Partly sunny, with a high near 39.
Tuesday Night
A 30 percent chance of rain. Mostly cloudy, with a low around 32.
Wednesday
Mostly cloudy, with a high near 43.
Wednesday Night
A 50 percent chance of rain. Mostly cloudy, with a low around 35.
Thursday
A 50 percent chance of rain. Mostly cloudy, with a high near 43.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.95°N 73.05°W (Elev. 151 ft)
Last Update:
2:14 pm EST Dec 4, 2025
Forecast Valid:
5pm EST Dec 4, 2025-6pm EST Dec 11, 2025
 
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Additional Resources

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Chance of Precipitation