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.

Mostly Cloudy

26°F

-3°C

Humidity 51%
Wind Speed Calm
Barometer 30.20 in (1022.8 mb)
Dewpoint 10°F (-12°C)
Visibility 10.00 mi
Last update 4 Feb 6:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Mostly cloudy, then gradually becoming mostly clear, with a low around 18. Wind chill values between 10 and 15. North wind around 6 mph.

    Low: 18 °F

    Decreasing
    Clouds

  • Thursday

    Thursday: Sunny, with a high near 30. Wind chill values between 10 and 20. North wind 5 to 7 mph.

    High: 30 °F

    Sunny

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 18. Wind chill values between 10 and 15. North wind 5 to 7 mph.

    Low: 18 °F

    Partly Cloudy

  • Friday

    Friday: Mostly cloudy, with a high near 27. Wind chill values between 10 and 20. Northeast wind around 6 mph becoming light and variable in the afternoon.

    High: 27 °F

    Mostly Cloudy

  • Friday Night

    Friday Night: Light snow likely, mainly after 1am. Cloudy, with a low around 18. Light southwest wind becoming west 8 to 13 mph in the evening. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.

    Low: 18 °F

    Chance Light
    Snow then
    Light Snow
    Likely

  • Saturday

    Saturday: Snow likely, mainly before 1pm. Mostly cloudy, with a temperature falling to around 15 by 5pm. Windy. Chance of precipitation is 60%. New snow accumulation of less than one inch possible.

    High: 22 °F⇓

    Snow Likely
    and Windy

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 8. Windy.

    Low: 8 °F

    Partly Cloudy
    and Windy

  • Sunday

    Sunday: Sunny and cold, with a high near 18. Blustery.

    High: 18 °F

    Cold and
    Blustery

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 12.

    Low: 12 °F

    Mostly Clear

Detailed Forecast

Tonight
Mostly cloudy, then gradually becoming mostly clear, with a low around 18. Wind chill values between 10 and 15. North wind around 6 mph.
Thursday
Sunny, with a high near 30. Wind chill values between 10 and 20. North wind 5 to 7 mph.
Thursday Night
Partly cloudy, with a low around 18. Wind chill values between 10 and 15. North wind 5 to 7 mph.
Friday
Mostly cloudy, with a high near 27. Wind chill values between 10 and 20. Northeast wind around 6 mph becoming light and variable in the afternoon.
Friday Night
Light snow likely, mainly after 1am. Cloudy, with a low around 18. Light southwest wind becoming west 8 to 13 mph in the evening. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.
Saturday
Snow likely, mainly before 1pm. Mostly cloudy, with a temperature falling to around 15 by 5pm. Windy. Chance of precipitation is 60%. New snow accumulation of less than one inch possible.
Saturday Night
Partly cloudy, with a low around 8. Windy.
Sunday
Sunny and cold, with a high near 18. Blustery.
Sunday Night
Mostly clear, with a low around 12.
Monday
Mostly sunny, with a high near 26.
Monday Night
Partly cloudy, with a low around 19.
Tuesday
Partly sunny, with a high near 31.
Tuesday Night
Mostly cloudy, with a low around 23.
Wednesday
Mostly sunny, with a high near 33.
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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:
1:52 pm EST Feb 4, 2026
Forecast Valid:
7pm EST Feb 4, 2026-6pm EST Feb 11, 2026
 
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Additional Resources

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Hourly Weather Forecast

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation