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.

Mostly Cloudy

40°F

4°C

Humidity 73%
Wind Speed SW 10 mph
Barometer 29.73 in (1006.9 mb)
Dewpoint 32°F (0°C)
Visibility 10.00 mi
Wind Chill34°F (1°C)
Last update 10 Dec 8:56 am EST
Extended Forecast for

Port Jefferson NY

  • Today

    Today: Rain likely, mainly after 4pm. Mostly cloudy, with a high near 47. Breezy, with a south wind 16 to 20 mph, with gusts as high as 33 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 47 °F

    Mostly Cloudy
    then Rain
    Likely and
    Breezy

  • Tonight

    Tonight: Rain, mainly before 10pm. Low around 30. Southwest wind 16 to 18 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

    Low: 30 °F

    Rain then
    Mostly Cloudy

  • Thursday

    Thursday: Mostly sunny, with a high near 37. Wind chill values between 20 and 25. Breezy, with a west wind 22 to 25 mph, with gusts as high as 36 mph.

    High: 37 °F

    Mostly Sunny
    and Breezy

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 26. Wind chill values between 10 and 20. Windy, with a west wind 24 to 26 mph.

    Low: 26 °F

    Partly Cloudy
    and Windy

  • Friday

    Friday: Mostly sunny, with a high near 35. Breezy, with a west wind 15 to 21 mph.

    High: 35 °F

    Mostly Sunny
    and Breezy
    then Mostly
    Sunny

  • Friday Night

    Friday Night: Partly cloudy, with a low around 27.

    Low: 27 °F

    Partly Cloudy

  • Saturday

    Saturday: Partly sunny, with a high near 39.

    High: 39 °F

    Partly Sunny

  • Saturday Night

    Saturday Night: A 30 percent chance of snow after 1am. Mostly cloudy, with a low around 28.

    Low: 28 °F

    Mostly Cloudy
    then Chance
    Snow

  • Sunday

    Sunday: A 30 percent chance of snow before 1pm. Mostly cloudy, with a high near 35.

    High: 35 °F

    Chance Snow

Detailed Forecast

Today
Rain likely, mainly after 4pm. Mostly cloudy, with a high near 47. Breezy, with a south wind 16 to 20 mph, with gusts as high as 33 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.
Tonight
Rain, mainly before 10pm. Low around 30. Southwest wind 16 to 18 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.
Thursday
Mostly sunny, with a high near 37. Wind chill values between 20 and 25. Breezy, with a west wind 22 to 25 mph, with gusts as high as 36 mph.
Thursday Night
Partly cloudy, with a low around 26. Wind chill values between 10 and 20. Windy, with a west wind 24 to 26 mph.
Friday
Mostly sunny, with a high near 35. Breezy, with a west wind 15 to 21 mph.
Friday Night
Partly cloudy, with a low around 27.
Saturday
Partly sunny, with a high near 39.
Saturday Night
A 30 percent chance of snow after 1am. Mostly cloudy, with a low around 28.
Sunday
A 30 percent chance of snow before 1pm. Mostly cloudy, with a high near 35.
Sunday Night
Partly cloudy, with a low around 20.
Monday
Sunny, with a high near 30.
Monday Night
Mostly cloudy, with a low around 22.
Tuesday
Partly sunny, with a high near 33.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.95°N 73.05°W (Elev. 151 ft)
Last Update:
2:32 am EST Dec 10, 2025
Forecast Valid:
9am EST Dec 10, 2025-6pm EST Dec 16, 2025
 
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Additional Resources

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High Temperature

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Chance of Precipitation