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

39°F

4°C

Humidity 45%
Wind Speed NW 9 mph
Barometer 30.28 in (1025.5 mb)
Dewpoint 19°F (-7°C)
Visibility 10.00 mi
Wind Chill33°F (1°C)
Last update 14 Mar 9:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Partly cloudy, with a low around 32. Northwest wind 5 to 9 mph becoming light after midnight. Winds could gust as high as 22 mph.

    Low: 32 °F

    Partly Cloudy

  • Sunday

    Sunday: Partly sunny, with a high near 48. Northeast wind 5 to 10 mph becoming southeast in the afternoon.

    High: 48 °F

    Partly Sunny

  • Sunday Night

    Sunday Night: Showers after 2am. Temperature falling to near 40 by 8pm, then rising to around 47 during the remainder of the night. Southeast wind 9 to 14 mph, with gusts as high as 24 mph. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.

    Low: 40 °F⇑

    Mostly Cloudy
    then Showers

  • Monday

    Monday: Showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. High near 58. Breezy, with a south wind 18 to 22 mph, with gusts as high as 39 mph. Chance of precipitation is 100%. New rainfall amounts between a half and three quarters of an inch possible.

    High: 58 °F

    Heavy Rain
    and Breezy

  • Monday Night

    Monday Night: Showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Low around 33. Windy, with a south wind 27 to 32 mph decreasing to 21 to 26 mph after midnight. Winds could gust as high as 49 mph. Chance of precipitation is 100%. New precipitation amounts between a half and three quarters of an inch possible.

    Low: 33 °F

    Heavy Rain
    and Windy

  • Tuesday

    Tuesday: A 30 percent chance of showers before 8am. Mostly sunny, with a high near 41.

    High: 41 °F

    Chance
    Showers then
    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 24.

    Low: 24 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 37.

    High: 37 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 29.

    Low: 29 °F

    Mostly Cloudy

Detailed Forecast

Tonight
Partly cloudy, with a low around 32. Northwest wind 5 to 9 mph becoming light after midnight. Winds could gust as high as 22 mph.
Sunday
Partly sunny, with a high near 48. Northeast wind 5 to 10 mph becoming southeast in the afternoon.
Sunday Night
Showers after 2am. Temperature falling to near 40 by 8pm, then rising to around 47 during the remainder of the night. Southeast wind 9 to 14 mph, with gusts as high as 24 mph. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.
Monday
Showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. High near 58. Breezy, with a south wind 18 to 22 mph, with gusts as high as 39 mph. Chance of precipitation is 100%. New rainfall amounts between a half and three quarters of an inch possible.
Monday Night
Showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Low around 33. Windy, with a south wind 27 to 32 mph decreasing to 21 to 26 mph after midnight. Winds could gust as high as 49 mph. Chance of precipitation is 100%. New precipitation amounts between a half and three quarters of an inch possible.
Tuesday
A 30 percent chance of showers before 8am. Mostly sunny, with a high near 41.
Tuesday Night
Partly cloudy, with a low around 24.
Wednesday
Mostly sunny, with a high near 37.
Wednesday Night
Mostly cloudy, with a low around 29.
Thursday
Mostly sunny, with a high near 44.
Thursday Night
Mostly cloudy, with a low around 32.
Friday
Mostly sunny, with a high near 47.
Friday Night
A 30 percent chance of rain. Partly cloudy, with a low around 34.
Saturday
A 30 percent chance of rain. Partly sunny, with a high near 47.
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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:
7:50 pm EDT Mar 14, 2026
Forecast Valid:
10pm EDT Mar 14, 2026-6pm EDT Mar 21, 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