National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Hazardous Weather Conditions

Current conditions at

Islip, Long Island Mac Arthur Airport (KISP)

Lat: 40.79°NLon: 73.1°WElev: 98ft.

Mostly Cloudy

55°F

13°C

Humidity 77%
Wind Speed SE 5 mph
Barometer 30.18 in (1021.8 mb)
Dewpoint 48°F (9°C)
Visibility 10.00 mi
Wind Chill54°F (12°C)
Last update 15 Oct 8:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: A 30 percent chance of showers after 5am. Increasing clouds, with a temperature falling to near 53 by 11pm, then rising to around 57 during the remainder of the night. Southeast wind 6 to 8 mph.

    Low: 53 °F⇑

    Partly Cloudy
    then Chance
    Showers

  • Friday

    Friday: Showers, with thunderstorms also possible after 2pm. High near 71. Southwest wind 11 to 14 mph. Chance of precipitation is 90%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    High: 71 °F

    Showers then
    Chance
    Showers

  • Friday Night

    Friday Night: A chance of showers and thunderstorms, then showers after 8pm. Low around 47. West wind 11 to 16 mph becoming northwest after midnight. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    Low: 47 °F

    Showers then
    Showers
    Likely

  • Saturday

    Saturday: Cloudy through mid morning, then gradual clearing, with a steady temperature around 50. Breezy, with a north wind 17 to 20 mph.

    High: 50 °F

    Cloudy and
    Breezy then
    Mostly Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 42. North wind 13 to 17 mph.

    Low: 42 °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

  • Monday

    Monday: Sunny, with a high near 61.

    High: 61 °F

    Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 50.

    Low: 50 °F

    Partly Cloudy

Detailed Forecast

Tonight
A 30 percent chance of showers after 5am. Increasing clouds, with a temperature falling to near 53 by 11pm, then rising to around 57 during the remainder of the night. Southeast wind 6 to 8 mph.
Friday
Showers, with thunderstorms also possible after 2pm. High near 71. Southwest wind 11 to 14 mph. Chance of precipitation is 90%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Friday Night
A chance of showers and thunderstorms, then showers after 8pm. Low around 47. West wind 11 to 16 mph becoming northwest after midnight. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Saturday
Cloudy through mid morning, then gradual clearing, with a steady temperature around 50. Breezy, with a north wind 17 to 20 mph.
Saturday Night
Mostly clear, with a low around 42. North wind 13 to 17 mph.
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 50.
Tuesday
Mostly sunny, with a high near 63.
Tuesday Night
Partly cloudy, with a low around 53.
Wednesday
Sunny, with a high near 63.
Wednesday Night
Mostly clear, with a low around 50.
Thursday
Mostly sunny, with a high near 60.
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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:
2:36 pm EDT Oct 15, 2026
Forecast Valid:
9pm EDT Oct 15, 2026-6pm EDT Oct 22, 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