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

54°F

12°C

Humidity 75%
Wind Speed SW 14 G 23 mph
Barometer 29.74 in (1007.2 mb)
Dewpoint 46°F (8°C)
Visibility 10.00 mi
Wind Chill50°F (10°C)
Last update 26 Mar 6:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Showers, mainly after 8pm. Low around 46. Breezy, with a south wind 14 to 21 mph, with gusts as high as 31 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.

    Low: 46 °F

    Breezy.
    Showers
    Likely then
    Showers

  • Friday

    Friday: Showers likely, mainly before 11am. Mostly cloudy, with a temperature falling to around 44 by noon. North wind 10 to 15 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

    High: 49 °F⇓

    Showers
    Likely then
    Slight Chance
    Showers

  • Friday Night

    Friday Night: Mostly cloudy, with a low around 32. North wind 7 to 10 mph.

    Low: 32 °F

    Mostly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 39. Wind chill values between 20 and 30. Northwest wind 11 to 14 mph.

    High: 39 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 31. Northwest wind 6 to 10 mph.

    Low: 31 °F

    Mostly Clear

  • Sunday

    Sunday: Mostly sunny, with a high near 45.

    High: 45 °F

    Mostly Sunny

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 42.

    Low: 42 °F

    Mostly Cloudy

  • Monday

    Monday: Partly sunny, with a high near 53.

    High: 53 °F

    Partly Sunny

  • Monday Night

    Monday Night: Mostly cloudy, with a low around 45.

    Low: 45 °F

    Mostly Cloudy

Detailed Forecast

Tonight
Showers, mainly after 8pm. Low around 46. Breezy, with a south wind 14 to 21 mph, with gusts as high as 31 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.
Friday
Showers likely, mainly before 11am. Mostly cloudy, with a temperature falling to around 44 by noon. North wind 10 to 15 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Friday Night
Mostly cloudy, with a low around 32. North wind 7 to 10 mph.
Saturday
Mostly sunny, with a high near 39. Wind chill values between 20 and 30. Northwest wind 11 to 14 mph.
Saturday Night
Mostly clear, with a low around 31. Northwest wind 6 to 10 mph.
Sunday
Mostly sunny, with a high near 45.
Sunday Night
Mostly cloudy, with a low around 42.
Monday
Partly sunny, with a high near 53.
Monday Night
Mostly cloudy, with a low around 45.
Tuesday
A 30 percent chance of rain after 8am. Mostly cloudy, with a high near 52.
Tuesday Night
A 40 percent chance of rain. Mostly cloudy, with a low around 46.
Wednesday
A 40 percent chance of rain. Mostly cloudy, with a high near 57.
Wednesday Night
A 40 percent chance of rain. Mostly cloudy, with a low around 47.
Thursday
A 30 percent chance of rain. Mostly cloudy, with a high near 57.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.96°N 73.08°W (Elev. 3 ft)
Last Update:
4:04 pm EDT Mar 26, 2026
Forecast Valid:
7pm EDT Mar 26, 2026-6pm EDT Apr 2, 2026
 
Forecast Discussion
 
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Additional Resources

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation