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

43°F

6°C

Humidity 56%
Wind Speed SW 15 G 25 mph
Barometer 30.42 in (1030.1 mb)
Dewpoint 28°F (-2°C)
Visibility 10.00 mi
Wind Chill36°F (2°C)
Last update 29 Mar 7:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Increasing clouds, with a low around 41. Southwest wind around 13 mph.

    Low: 41 °F

    Increasing
    Clouds

  • Monday

    Monday: A 20 percent chance of showers after 2pm. Partly sunny, with a high near 58. Southwest wind 14 to 18 mph.

    High: 58 °F

    Partly Sunny
    then Slight
    Chance
    Showers

  • Monday Night

    Monday Night: A slight chance of showers before 8pm, then a chance of rain after 2am. Mostly cloudy, with a low around 48. Southwest wind 7 to 13 mph. Chance of precipitation is 30%.

    Low: 48 °F

    Mostly Cloudy
    then Chance
    Rain

  • Tuesday

    Tuesday: A 30 percent chance of rain before 2pm. Partly sunny, with a high near 61. Southwest wind 8 to 11 mph.

    High: 61 °F

    Chance Rain

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 51. South wind around 14 mph.

    Low: 51 °F

    Mostly Cloudy

  • Wednesday

    Wednesday: Rain likely after 2pm. Partly sunny, with a high near 67. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

    High: 67 °F

    Partly Sunny
    then Rain
    Likely

  • Wednesday Night

    Wednesday Night: Rain likely and possibly a thunderstorm before 2am, then a chance of rain and thunderstorms after 2am. Mostly cloudy, with a low around 45. Chance of precipitation is 70%.

    Low: 45 °F

    Rain Likely

  • Thursday

    Thursday: A 40 percent chance of rain. Cloudy, with a high near 53.

    High: 53 °F

    Chance Rain

  • Thursday Night

    Thursday Night: Rain likely, mainly after 2am. Cloudy, with a low around 41. Chance of precipitation is 60%.

    Low: 41 °F

    Rain Likely

Detailed Forecast

Tonight
Increasing clouds, with a low around 41. Southwest wind around 13 mph.
Monday
A 20 percent chance of showers after 2pm. Partly sunny, with a high near 58. Southwest wind 14 to 18 mph.
Monday Night
A slight chance of showers before 8pm, then a chance of rain after 2am. Mostly cloudy, with a low around 48. Southwest wind 7 to 13 mph. Chance of precipitation is 30%.
Tuesday
A 30 percent chance of rain before 2pm. Partly sunny, with a high near 61. Southwest wind 8 to 11 mph.
Tuesday Night
Mostly cloudy, with a low around 51. South wind around 14 mph.
Wednesday
Rain likely after 2pm. Partly sunny, with a high near 67. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Wednesday Night
Rain likely and possibly a thunderstorm before 2am, then a chance of rain and thunderstorms after 2am. Mostly cloudy, with a low around 45. Chance of precipitation is 70%.
Thursday
A 40 percent chance of rain. Cloudy, with a high near 53.
Thursday Night
Rain likely, mainly after 2am. Cloudy, with a low around 41. Chance of precipitation is 60%.
Friday
Rain likely, mainly before 8am. Cloudy, with a high near 54. Chance of precipitation is 60%.
Friday Night
A 50 percent chance of rain. Cloudy, with a low around 40.
Saturday
A 30 percent chance of rain. Mostly cloudy, with a high near 52.
Saturday Night
A 40 percent chance of rain. Cloudy, with a low around 40.
Sunday
A 50 percent chance of rain. Mostly cloudy, with a high near 58.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.93°N 73.06°W (Elev. 161 ft)
Last Update:
7:43 pm EDT Mar 29, 2026
Forecast Valid:
8pm EDT Mar 29, 2026-6pm EDT Apr 5, 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