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.

Fair

29°F

-2°C

Humidity 82%
Wind Speed SE 3 mph
Barometer 30.16 in (1021.4 mb)
Dewpoint 24°F (-4°C)
Visibility 10.00 mi
Last update 27 Feb 8:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Patchy fog after 2am. Otherwise, partly cloudy, with a low around 28. Calm wind.

    Low: 28 °F

    Mostly Clear
    then Patchy
    Fog

  • Saturday

    Saturday: Patchy fog before 9am. Otherwise, mostly sunny, with a high near 44. Calm wind becoming southwest around 6 mph.

    High: 44 °F

    Patchy Fog
    then Mostly
    Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 28. Calm wind.

    Low: 28 °F

    Partly Cloudy

  • Sunday

    Sunday: Snow showers likely, mainly between 10am and 4pm. Cloudy, then becoming mostly sunny during the afternoon, with a high near 37. Northwest wind 3 to 8 mph. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.

    High: 37 °F

    Snow Showers
    Likely

  • Sunday Night

    Sunday Night: A 30 percent chance of snow showers before 7pm. Mostly clear, with a low around 17. North wind around 9 mph.

    Low: 17 °F

    Chance Snow
    Showers then
    Mostly Clear

  • Monday

    Monday: Partly sunny, with a high near 28.

    High: 28 °F

    Partly Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 20.

    Low: 20 °F

    Partly Cloudy

  • Tuesday

    Tuesday: A chance of rain and snow before 1pm, then a chance of rain. Mostly cloudy, with a high near 40. Chance of precipitation is 50%.

    High: 40 °F

    Chance
    Rain/Snow

  • Tuesday Night

    Tuesday Night: Rain likely. Cloudy, with a low around 36. Chance of precipitation is 70%.

    Low: 36 °F

    Rain Likely

Detailed Forecast

Tonight
Patchy fog after 2am. Otherwise, partly cloudy, with a low around 28. Calm wind.
Saturday
Patchy fog before 9am. Otherwise, mostly sunny, with a high near 44. Calm wind becoming southwest around 6 mph.
Saturday Night
Partly cloudy, with a low around 28. Calm wind.
Sunday
Snow showers likely, mainly between 10am and 4pm. Cloudy, then becoming mostly sunny during the afternoon, with a high near 37. Northwest wind 3 to 8 mph. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.
Sunday Night
A 30 percent chance of snow showers before 7pm. Mostly clear, with a low around 17. North wind around 9 mph.
Monday
Partly sunny, with a high near 28.
Monday Night
Partly cloudy, with a low around 20.
Tuesday
A chance of rain and snow before 1pm, then a chance of rain. Mostly cloudy, with a high near 40. Chance of precipitation is 50%.
Tuesday Night
Rain likely. Cloudy, with a low around 36. Chance of precipitation is 70%.
Wednesday
A 30 percent chance of rain before 1pm. Mostly cloudy, with a high near 44.
Wednesday Night
A 30 percent chance of rain. Mostly cloudy, with a low around 33.
Thursday
A 40 percent chance of rain. Cloudy, with a high near 43.
Thursday Night
Rain likely. Cloudy, with a low around 36. Chance of precipitation is 60%.
Friday
A 40 percent chance of rain. Cloudy, with a high near 41.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.93°N 73.06°W (Elev. 161 ft)
Last Update:
8:51 pm EST Feb 27, 2026
Forecast Valid:
9pm EST Feb 27, 2026-6pm EST Mar 6, 2026
 
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Additional Resources

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Hourly Weather Forecast

National Digital Forecast Database

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation