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

47°F

8°C

Humidity 61%
Wind Speed S 10 mph
Barometer 30.05 in (1017.6 mb)
Dewpoint 34°F (1°C)
Visibility 10.00 mi
Wind Chill42°F (6°C)
Last update 28 Feb 1:56 pm EST
Extended Forecast for

Port Jefferson NY

  • This Afternoon

    This Afternoon: Sunny, with a steady temperature around 46. South wind around 6 mph.

    High: 46 °F

    Sunny

  • Tonight

    Tonight: Patchy fog between 9pm and 2am. Otherwise, increasing clouds, with a low around 27. Calm wind becoming north around 5 mph after midnight.

    Low: 27 °F

    Patchy Fog

  • Sunday

    Sunday: Snow likely, mainly before 1pm. Cloudy, then gradually becoming mostly sunny, with a high near 34. Wind chill values between 20 and 25. North wind 5 to 9 mph. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.

    High: 34 °F

    Snow Likely

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 15. Wind chill values between 5 and 10. North wind around 9 mph, with gusts as high as 22 mph.

    Low: 15 °F

    Mostly Clear

  • Monday

    Monday: Sunny, with a high near 28. North wind 5 to 7 mph becoming calm in the afternoon.

    High: 28 °F

    Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 19.

    Low: 19 °F

    Mostly Clear

  • Tuesday

    Tuesday: A chance of rain and snow before 10am, then rain likely. Mostly cloudy, with a high near 41. Chance of precipitation is 70%.

    High: 41 °F

    Chance
    Rain/Snow
    then Rain
    Likely

  • Tuesday Night

    Tuesday Night: Rain. Low around 35. Chance of precipitation is 90%.

    Low: 35 °F

    Rain

  • Wednesday

    Wednesday: Mostly cloudy, with a high near 45.

    High: 45 °F

    Mostly Cloudy

Detailed Forecast

This Afternoon
Sunny, with a steady temperature around 46. South wind around 6 mph.
Tonight
Patchy fog between 9pm and 2am. Otherwise, increasing clouds, with a low around 27. Calm wind becoming north around 5 mph after midnight.
Sunday
Snow likely, mainly before 1pm. Cloudy, then gradually becoming mostly sunny, with a high near 34. Wind chill values between 20 and 25. North wind 5 to 9 mph. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.
Sunday Night
Mostly clear, with a low around 15. Wind chill values between 5 and 10. North wind around 9 mph, with gusts as high as 22 mph.
Monday
Sunny, with a high near 28. North wind 5 to 7 mph becoming calm in the afternoon.
Monday Night
Mostly clear, with a low around 19.
Tuesday
A chance of rain and snow before 10am, then rain likely. Mostly cloudy, with a high near 41. Chance of precipitation is 70%.
Tuesday Night
Rain. Low around 35. Chance of precipitation is 90%.
Wednesday
Mostly cloudy, with a high near 45.
Wednesday Night
A 40 percent chance of rain. Cloudy, with a low around 34.
Thursday
A 40 percent chance of rain. Cloudy, with a high near 48.
Thursday Night
A 50 percent chance of rain. Cloudy, with a low around 37.
Friday
A 40 percent chance of rain. Cloudy, with a high near 46.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.93°N 73.06°W (Elev. 161 ft)
Last Update:
1:49 pm EST Feb 28, 2026
Forecast Valid:
2pm EST Feb 28, 2026-6pm EST Mar 6, 2026
 
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Additional Resources

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation