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.

A Few Clouds

27°F

-3°C

Humidity 32%
Wind Speed NW 15 mph
Barometer 30.16 in (1021.5 mb)
Dewpoint 1°F (-17°C)
Visibility 10.00 mi
Wind Chill15°F (-9°C)
Last update 9 Feb 4:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Mostly cloudy, with a low around 23. Wind chill values between 15 and 20. Northwest wind 5 to 10 mph.

    Low: 23 °F

    Mostly Cloudy

  • Tuesday

    Tuesday: A 20 percent chance of snow after 1pm. Mostly cloudy, with a high near 35. Wind chill values between 25 and 30. Calm wind becoming south 5 to 7 mph in the afternoon.

    High: 35 °F

    Partly Sunny
    then Slight
    Chance Snow

  • Tuesday Night

    Tuesday Night: A chance of rain and snow before 4am, then a slight chance of snow. Cloudy, then gradually becoming partly cloudy, with a low around 32. South wind 7 to 10 mph becoming west after midnight. Chance of precipitation is 50%.

    Low: 32 °F

    Chance
    Rain/Snow

  • Wednesday

    Wednesday: Mostly sunny, with a high near 37. Wind chill values between 25 and 30. Breezy, with a west wind 13 to 20 mph.

    High: 37 °F

    Mostly Sunny
    then Mostly
    Sunny and
    Breezy

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 26. Breezy, with a west wind 18 to 20 mph.

    Low: 26 °F

    Partly Cloudy
    and Breezy
    then Partly
    Cloudy

  • Thursday

    Thursday: Mostly sunny, with a high near 33.

    High: 33 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 23.

    Low: 23 °F

    Partly Cloudy

  • Friday

    Friday: Mostly sunny, with a high near 32.

    High: 32 °F

    Mostly Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 24.

    Low: 24 °F

    Mostly Clear

Detailed Forecast

Tonight
Mostly cloudy, with a low around 23. Wind chill values between 15 and 20. Northwest wind 5 to 10 mph.
Tuesday
A 20 percent chance of snow after 1pm. Mostly cloudy, with a high near 35. Wind chill values between 25 and 30. Calm wind becoming south 5 to 7 mph in the afternoon.
Tuesday Night
A chance of rain and snow before 4am, then a slight chance of snow. Cloudy, then gradually becoming partly cloudy, with a low around 32. South wind 7 to 10 mph becoming west after midnight. Chance of precipitation is 50%.
Wednesday
Mostly sunny, with a high near 37. Wind chill values between 25 and 30. Breezy, with a west wind 13 to 20 mph.
Wednesday Night
Partly cloudy, with a low around 26. Breezy, with a west wind 18 to 20 mph.
Thursday
Mostly sunny, with a high near 33.
Thursday Night
Partly cloudy, with a low around 23.
Friday
Mostly sunny, with a high near 32.
Friday Night
Mostly clear, with a low around 24.
Saturday
Sunny, with a high near 34.
Saturday Night
Partly cloudy, with a low around 26.
Sunday
A chance of rain and snow. Mostly cloudy, with a high near 36. Chance of precipitation is 40%.
Sunday Night
Rain likely. Cloudy, with a low around 33. Breezy. Chance of precipitation is 70%.
Washington's Birthday
Rain likely. Mostly cloudy, with a high near 39. Breezy. Chance of precipitation is 60%.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.96°N 73.08°W (Elev. 3 ft)
Last Update:
1:12 pm EST Feb 9, 2026
Forecast Valid:
5pm EST Feb 9, 2026-6pm EST Feb 16, 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