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

67°F

19°C

Humidity 73%
Wind Speed N 9 mph
Barometer 29.96 in (1014.4 mb)
Dewpoint 58°F (14°C)
Visibility 10.00 mi
Last update 14 Oct 10:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Mostly clear, with a low around 54. North wind around 11 mph, with gusts as high as 21 mph.

    Low: 54 °F

    Mostly Clear

  • Thursday

    Thursday: Sunny, with a high near 60. North wind 5 to 11 mph, with gusts as high as 21 mph.

    High: 60 °F

    Sunny

  • Thursday Night

    Thursday Night: Showers likely, mainly after 5am. Increasing clouds, with a low around 53. Southeast wind 5 to 8 mph. Chance of precipitation is 60%.

    Low: 53 °F

    Mostly Clear
    then Showers
    Likely

  • Friday

    Friday: Showers, with thunderstorms also possible after 5pm. High near 70. Southwest wind 11 to 13 mph, with gusts as high as 24 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    High: 70 °F

    Showers

  • Friday Night

    Friday Night: Showers and thunderstorms. Low around 49. Southwest wind 14 to 18 mph becoming northwest after midnight. Winds could gust as high as 30 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    Low: 49 °F

    Showers

  • Saturday

    Saturday: A 30 percent chance of showers before 8am. Partly sunny, with a steady temperature around 51. Breezy.

    High: 51 °F

    Breezy.
    Chance
    Showers then
    Mostly Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 43.

    Low: 43 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 56.

    High: 56 °F

    Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 48.

    Low: 48 °F

    Mostly Clear

Detailed Forecast

Tonight
Mostly clear, with a low around 54. North wind around 11 mph, with gusts as high as 21 mph.
Thursday
Sunny, with a high near 60. North wind 5 to 11 mph, with gusts as high as 21 mph.
Thursday Night
Showers likely, mainly after 5am. Increasing clouds, with a low around 53. Southeast wind 5 to 8 mph. Chance of precipitation is 60%.
Friday
Showers, with thunderstorms also possible after 5pm. High near 70. Southwest wind 11 to 13 mph, with gusts as high as 24 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Friday Night
Showers and thunderstorms. Low around 49. Southwest wind 14 to 18 mph becoming northwest after midnight. Winds could gust as high as 30 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Saturday
A 30 percent chance of showers before 8am. Partly sunny, with a steady temperature around 51. Breezy.
Saturday Night
Mostly clear, with a low around 43.
Sunday
Sunny, with a high near 56.
Sunday Night
Mostly clear, with a low around 48.
Monday
Sunny, with a high near 61.
Monday Night
Partly cloudy, with a low around 51.
Tuesday
Mostly sunny, with a high near 63.
Tuesday Night
Partly cloudy, with a low around 51.
Wednesday
Sunny, with a high near 63.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.95°N 73.05°W (Elev. 151 ft)
Last Update:
7:37 pm EDT Oct 14, 2026
Forecast Valid:
11pm EDT Oct 14, 2026-6pm EDT Oct 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