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

38°F

3°C

Humidity 41%
Wind Speed N 18 G 26 mph
Barometer 30.38 in (1028.7 mb)
Dewpoint 16°F (-9°C)
Visibility 10.00 mi
Wind Chill28°F (-2°C)
Last update 24 Mar 9:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Today

    Today: Sunny, with a high near 46. Northwest wind 5 to 11 mph.

    High: 46 °F

    Sunny

  • Tonight

    Tonight: Increasing clouds, with a low around 35. South wind around 7 mph.

    Low: 35 °F

    Increasing
    Clouds

  • Wednesday

    Wednesday: Partly sunny, with a high near 49. Southwest wind 3 to 8 mph.

    High: 49 °F

    Partly Sunny

  • Wednesday Night

    Wednesday Night: Cloudy, with a low around 39. South wind around 7 mph.

    Low: 39 °F

    Cloudy

  • Thursday

    Thursday: Mostly cloudy, with a high near 56. Southwest wind 7 to 11 mph, with gusts as high as 21 mph.

    High: 56 °F

    Mostly Cloudy

  • Thursday Night

    Thursday Night: Rain likely, mainly after 2am. Mostly cloudy, with a low around 45. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

    Low: 45 °F

    Chance Rain
    then Rain
    Likely

  • Friday

    Friday: Rain likely, mainly before 8am. Cloudy, then gradually becoming mostly sunny, with a high near 51. Chance of precipitation is 60%.

    High: 51 °F

    Rain Likely

  • Friday Night

    Friday Night: Partly cloudy, with a low around 26.

    Low: 26 °F

    Partly Cloudy

  • Saturday

    Saturday: Sunny, with a high near 41.

    High: 41 °F

    Sunny

Detailed Forecast

Today
Sunny, with a high near 46. Northwest wind 5 to 11 mph.
Tonight
Increasing clouds, with a low around 35. South wind around 7 mph.
Wednesday
Partly sunny, with a high near 49. Southwest wind 3 to 8 mph.
Wednesday Night
Cloudy, with a low around 39. South wind around 7 mph.
Thursday
Mostly cloudy, with a high near 56. Southwest wind 7 to 11 mph, with gusts as high as 21 mph.
Thursday Night
Rain likely, mainly after 2am. Mostly cloudy, with a low around 45. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.
Friday
Rain likely, mainly before 8am. Cloudy, then gradually becoming mostly sunny, with a high near 51. Chance of precipitation is 60%.
Friday Night
Partly cloudy, with a low around 26.
Saturday
Sunny, with a high near 41.
Saturday Night
Mostly clear, with a low around 31.
Sunday
Sunny, with a high near 47.
Sunday Night
Mostly cloudy, with a low around 36.
Monday
Partly sunny, with a high near 52.
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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:
3:49 am EDT Mar 24, 2026
Forecast Valid:
10am EDT Mar 24, 2026-6pm EDT Mar 30, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

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