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

38°F

3°C

Humidity 55%
Wind Speed S 7 mph
Barometer 30.11 in (1019.7 mb)
Dewpoint 23°F (-5°C)
Visibility 10.00 mi
Wind Chill33°F (1°C)
Last update 27 Feb 2:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Mostly clear, with a low around 30. Light south wind.

    Low: 30 °F

    Mostly Clear

  • Saturday

    Saturday: Mostly sunny, with a high near 43. Southwest wind around 6 mph.

    High: 43 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 31. Calm wind becoming north around 6 mph after midnight.

    Low: 31 °F

    Partly Cloudy

  • Sunday

    Sunday: Snow showers likely, mainly between 10am and 4pm. Mostly cloudy, with a high near 37. Northwest wind 7 to 14 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: Mostly clear, with a low around 20. North wind 15 to 17 mph.

    Low: 20 °F

    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 23.

    Low: 23 °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 35. Chance of precipitation is 70%.

    Low: 35 °F

    Rain Likely

Detailed Forecast

Tonight
Mostly clear, with a low around 30. Light south wind.
Saturday
Mostly sunny, with a high near 43. Southwest wind around 6 mph.
Saturday Night
Partly cloudy, with a low around 31. Calm wind becoming north around 6 mph after midnight.
Sunday
Snow showers likely, mainly between 10am and 4pm. Mostly cloudy, with a high near 37. Northwest wind 7 to 14 mph. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.
Sunday Night
Mostly clear, with a low around 20. North wind 15 to 17 mph.
Monday
Partly sunny, with a high near 28.
Monday Night
Partly cloudy, with a low around 23.
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 35. 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 36.
Thursday
A 40 percent chance of rain. Cloudy, with a high near 42.
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 40.
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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:
12:50 pm EST Feb 27, 2026
Forecast Valid:
3pm EST Feb 27, 2026-6pm EST Mar 6, 2026
 
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Additional Resources

Radar & Satellite Image

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Hourly Weather Forecast

National Digital Forecast Database

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation