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.

Overcast

32°F

0°C

Humidity 73%
Wind Speed N 13 mph
Barometer 30.19 in (1022.2 mb)
Dewpoint 24°F (-4°C)
Visibility 10.00 mi
Wind Chill22°F (-6°C)
Last update 1 Mar 11:56 am EST
Extended Forecast for

Port Jefferson NY

  • This Afternoon

    This Afternoon: Snow likely before 1pm. Cloudy early, then gradual clearing, with a high near 34. North wind around 10 mph. Chance of precipitation is 60%. Total daytime snow accumulation of less than a half inch possible.

    High: 34 °F

    Snow Likely

  • Tonight

    Tonight: Mostly clear, with a low around 19. Wind chill values between 5 and 15. North wind 11 to 14 mph.

    Low: 19 °F

    Mostly Clear

  • Monday

    Monday: Mostly sunny, with a high near 28. Wind chill values between 5 and 15. North wind 5 to 10 mph becoming light and variable in the afternoon.

    High: 28 °F

    Mostly Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 24. Wind chill values between 15 and 20. South wind around 6 mph.

    Low: 24 °F

    Mostly Clear

  • Tuesday

    Tuesday: A chance of snow before 10am, then a chance of rain and snow between 10am and 1pm, then rain after 1pm. High near 39. South wind 6 to 8 mph. Chance of precipitation is 80%. New snow accumulation of less than a half inch possible.

    High: 39 °F

    Chance
    Rain/Snow
    then
    Rain/Snow

  • Tuesday Night

    Tuesday Night: Rain. Low around 38. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.

    Low: 38 °F

    Rain

  • Wednesday

    Wednesday: A 30 percent chance of rain before 1pm. Partly sunny, with a high near 43.

    High: 43 °F

    Chance Rain

  • Wednesday Night

    Wednesday Night: A 50 percent chance of rain. Mostly cloudy, with a low around 38.

    Low: 38 °F

    Chance Rain

  • Thursday

    Thursday: A 40 percent chance of rain. Cloudy, with a high near 48.

    High: 48 °F

    Chance Rain

Detailed Forecast

This Afternoon
Snow likely before 1pm. Cloudy early, then gradual clearing, with a high near 34. North wind around 10 mph. Chance of precipitation is 60%. Total daytime snow accumulation of less than a half inch possible.
Tonight
Mostly clear, with a low around 19. Wind chill values between 5 and 15. North wind 11 to 14 mph.
Monday
Mostly sunny, with a high near 28. Wind chill values between 5 and 15. North wind 5 to 10 mph becoming light and variable in the afternoon.
Monday Night
Mostly clear, with a low around 24. Wind chill values between 15 and 20. South wind around 6 mph.
Tuesday
A chance of snow before 10am, then a chance of rain and snow between 10am and 1pm, then rain after 1pm. High near 39. South wind 6 to 8 mph. Chance of precipitation is 80%. New snow accumulation of less than a half inch possible.
Tuesday Night
Rain. Low around 38. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.
Wednesday
A 30 percent chance of rain before 1pm. Partly sunny, with a high near 43.
Wednesday Night
A 50 percent chance of rain. Mostly cloudy, with a low around 38.
Thursday
A 40 percent chance of rain. Cloudy, with a high near 48.
Thursday Night
Rain likely, mainly after 1am. Cloudy, with a low around 39. Chance of precipitation is 60%.
Friday
A 50 percent chance of rain. Cloudy, with a high near 42.
Friday Night
A 30 percent chance of rain. Cloudy, with a low around 39.
Saturday
Cloudy, with a high near 50.
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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:
11:15 am EST Mar 1, 2026
Forecast Valid:
12pm EST Mar 1, 2026-6pm EST Mar 7, 2026
 
Forecast Discussion
 
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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