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.

Mostly Cloudy

46°F

8°C

Humidity 58%
Wind Speed N 10 mph
Barometer 29.91 in (1012.7 mb)
Dewpoint 32°F (0°C)
Visibility 10.00 mi
Wind Chill41°F (5°C)
Last update 14 Nov 11:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Overnight

    Overnight: Partly cloudy, with a low around 37. Northwest wind 9 to 11 mph.

    Low: 37 °F

    Partly Cloudy

  • Saturday

    Saturday: A 20 percent chance of showers after 4pm. Increasing clouds, with a high near 54. North wind around 8 mph becoming southwest in the afternoon.

    High: 54 °F

    Sunny then
    Slight Chance
    Showers

  • Saturday Night

    Saturday Night: Showers, mainly between 7pm and 1am. Temperature rising to around 56 by 1am. South wind 10 to 17 mph. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.

    Low: 48 °F⇑

    Showers

  • Sunday

    Sunday: A 20 percent chance of showers before 10am. Cloudy through mid morning, then gradual clearing, with a temperature falling to around 49 by 5pm. Breezy, with a west wind 18 to 24 mph, with gusts as high as 36 mph.

    High: 57 °F⇓

    Breezy.
    Slight Chance
    Showers then
    Mostly Sunny

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 36. Breezy, with a west wind 22 to 24 mph, with gusts as high as 34 mph.

    Low: 36 °F

    Partly Cloudy
    and Breezy

  • Monday

    Monday: Mostly sunny, with a high near 45. Breezy.

    High: 45 °F

    Mostly Sunny
    and Breezy

  • Monday Night

    Monday Night: Mostly clear, with a low around 36. Breezy.

    Low: 36 °F

    Mostly Clear
    and Breezy
    then Mostly
    Clear

  • Tuesday

    Tuesday: Mostly sunny, with a high near 47.

    High: 47 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 36.

    Low: 36 °F

    Partly Cloudy

Detailed Forecast

Overnight
Partly cloudy, with a low around 37. Northwest wind 9 to 11 mph.
Saturday
A 20 percent chance of showers after 4pm. Increasing clouds, with a high near 54. North wind around 8 mph becoming southwest in the afternoon.
Saturday Night
Showers, mainly between 7pm and 1am. Temperature rising to around 56 by 1am. South wind 10 to 17 mph. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.
Sunday
A 20 percent chance of showers before 10am. Cloudy through mid morning, then gradual clearing, with a temperature falling to around 49 by 5pm. Breezy, with a west wind 18 to 24 mph, with gusts as high as 36 mph.
Sunday Night
Partly cloudy, with a low around 36. Breezy, with a west wind 22 to 24 mph, with gusts as high as 34 mph.
Monday
Mostly sunny, with a high near 45. Breezy.
Monday Night
Mostly clear, with a low around 36. Breezy.
Tuesday
Mostly sunny, with a high near 47.
Tuesday Night
Partly cloudy, with a low around 36.
Wednesday
Sunny, with a high near 48.
Wednesday Night
Partly cloudy, with a low around 37.
Thursday
Partly sunny, with a high near 50.
Thursday Night
A 40 percent chance of rain. Mostly cloudy, with a low around 42.
Friday
A 30 percent chance of rain. Mostly cloudy, with a high near 53.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.95°N 73.05°W (Elev. 151 ft)
Last Update:
10:06 pm EST Nov 14, 2025
Forecast Valid:
12am EST Nov 15, 2025-6pm EST Nov 21, 2025
 
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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