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.

Overcast

47°F

8°C

Humidity 71%
Wind Speed SW 14 G 22 mph
Barometer 29.44 in (996.9 mb)
Dewpoint 38°F (3°C)
Visibility 10.00 mi
Wind Chill41°F (5°C)
Last update 10 Dec 6:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Rain before 10pm. Low around 29. Breezy, with a southwest wind 16 to 21 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

    Low: 29 °F

    Rain then
    Mostly Cloudy
    and Breezy

  • Thursday

    Thursday: A 20 percent chance of snow showers after 1pm. Mostly sunny, with a steady temperature around 32. Wind chill values between 15 and 20. Windy, with a west wind 23 to 26 mph, with gusts as high as 43 mph.

    High: 32 °F

    Sunny and
    Breezy then
    Slight Chance
    Snow Showers
    and Windy

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 26. Wind chill values between 10 and 15. Windy, with a west wind 23 to 28 mph, with gusts as high as 41 mph.

    Low: 26 °F

    Partly Cloudy
    and Windy

  • Friday

    Friday: Mostly sunny, with a high near 35. Wind chill values between 10 and 20. Breezy, with a west wind 14 to 20 mph.

    High: 35 °F

    Mostly Sunny
    and Breezy
    then Mostly
    Sunny

  • Friday Night

    Friday Night: Partly cloudy, with a low around 27. West wind 7 to 10 mph.

    Low: 27 °F

    Partly Cloudy

  • Saturday

    Saturday: Partly sunny, with a high near 39.

    High: 39 °F

    Partly Sunny

  • Saturday Night

    Saturday Night: A 40 percent chance of snow after 1am. Mostly cloudy, with a low around 27.

    Low: 27 °F

    Mostly Cloudy
    then Chance
    Snow

  • Sunday

    Sunday: A 40 percent chance of snow before 1pm. Mostly cloudy, with a high near 33.

    High: 33 °F

    Chance Snow

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 21.

    Low: 21 °F

    Partly Cloudy

Detailed Forecast

Tonight
Rain before 10pm. Low around 29. Breezy, with a southwest wind 16 to 21 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.
Thursday
A 20 percent chance of snow showers after 1pm. Mostly sunny, with a steady temperature around 32. Wind chill values between 15 and 20. Windy, with a west wind 23 to 26 mph, with gusts as high as 43 mph.
Thursday Night
Partly cloudy, with a low around 26. Wind chill values between 10 and 15. Windy, with a west wind 23 to 28 mph, with gusts as high as 41 mph.
Friday
Mostly sunny, with a high near 35. Wind chill values between 10 and 20. Breezy, with a west wind 14 to 20 mph.
Friday Night
Partly cloudy, with a low around 27. West wind 7 to 10 mph.
Saturday
Partly sunny, with a high near 39.
Saturday Night
A 40 percent chance of snow after 1am. Mostly cloudy, with a low around 27.
Sunday
A 40 percent chance of snow before 1pm. Mostly cloudy, with a high near 33.
Sunday Night
Partly cloudy, with a low around 21.
Monday
Sunny, with a high near 31.
Monday Night
Mostly cloudy, with a low around 24.
Tuesday
Mostly sunny, with a high near 34.
Tuesday Night
Partly cloudy, with a low around 27.
Wednesday
Partly sunny, with a high near 41.
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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:
5:54 pm EST Dec 10, 2025
Forecast Valid:
7pm EST Dec 10, 2025-6pm EST Dec 17, 2025
 
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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