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.

Fair

54°F

12°C

Humidity 67%
Wind Speed W 9 mph
Barometer 29.89 in (1012.0 mb)
Dewpoint 43°F (6°C)
Visibility 10.00 mi
Wind Chill51°F (11°C)
Last update 10 Nov 9:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Mostly clear, with a low around 47. West wind 10 to 13 mph.

    Low: 47 °F

    Mostly Clear

  • Veterans Day

    Veterans Day: Mostly sunny, with a high near 59. West wind 6 to 8 mph becoming southwest in the afternoon.

    High: 59 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: A 20 percent chance of rain after 4am. Mostly cloudy, with a low around 48. Southeast wind 5 to 8 mph.

    Low: 48 °F

    Mostly Cloudy
    then Slight
    Chance Rain

  • Thursday

    Thursday: Rain, mainly after 1pm. High near 59. East wind 11 to 14 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 59 °F

    Chance Rain
    then Rain

  • Thursday Night

    Thursday Night: Rain. Low around 45. Northeast wind 14 to 18 mph. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.

    Low: 45 °F

    Rain

  • Friday

    Friday: Rain. High near 50. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.

    High: 50 °F

    Rain

  • Friday Night

    Friday Night: A 50 percent chance of rain. Cloudy, with a low around 39.

    Low: 39 °F

    Chance Rain

  • Saturday

    Saturday: A 30 percent chance of rain before 1pm. Mostly cloudy, with a high near 48.

    High: 48 °F

    Chance Rain

  • Saturday Night

    Saturday Night: Mostly cloudy, with a low around 41.

    Low: 41 °F

    Mostly Cloudy

Detailed Forecast

Tonight
Mostly clear, with a low around 47. West wind 10 to 13 mph.
Veterans Day
Mostly sunny, with a high near 59. West wind 6 to 8 mph becoming southwest in the afternoon.
Wednesday Night
A 20 percent chance of rain after 4am. Mostly cloudy, with a low around 48. Southeast wind 5 to 8 mph.
Thursday
Rain, mainly after 1pm. High near 59. East wind 11 to 14 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.
Thursday Night
Rain. Low around 45. Northeast wind 14 to 18 mph. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.
Friday
Rain. High near 50. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.
Friday Night
A 50 percent chance of rain. Cloudy, with a low around 39.
Saturday
A 30 percent chance of rain before 1pm. Mostly cloudy, with a high near 48.
Saturday Night
Mostly cloudy, with a low around 41.
Sunday
Mostly sunny, with a high near 51.
Sunday Night
Partly cloudy, with a low around 40.
Monday
Mostly sunny, with a high near 51.
Monday Night
Partly cloudy, with a low around 39.
Tuesday
Sunny, with a high near 51.
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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:
6:08 pm EST Nov 10, 2026
Forecast Valid:
10pm EST Nov 10, 2026-6pm EST Nov 17, 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