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

47°F

8°C

Humidity 29%
Wind Speed S 20 G 28 mph
Barometer 30.51 in (1033.2 mb)
Dewpoint 16°F (-9°C)
Visibility 10.00 mi
Wind Chill40°F (4°C)
Last update 29 Mar 1:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • This Afternoon

    This Afternoon: Mostly sunny, with a high near 47. Southwest wind 14 to 16 mph.

    High: 47 °F

    Mostly Sunny

  • Tonight

    Tonight: Increasing clouds, with a low around 43. Southwest wind around 18 mph.

    Low: 43 °F

    Increasing
    Clouds

  • Monday

    Monday: A 20 percent chance of showers after 2pm. Partly sunny, with a high near 56. Southwest wind around 18 mph.

    High: 56 °F

    Partly Sunny
    then Slight
    Chance
    Showers

  • Monday Night

    Monday Night: A slight chance of showers before 8pm, then a slight chance of showers after 2am. Mostly cloudy, with a low around 49. Southwest wind 11 to 15 mph. Chance of precipitation is 20%.

    Low: 49 °F

    Mostly Cloudy
    then Slight
    Chance
    Showers

  • Tuesday

    Tuesday: A 20 percent chance of showers before 2pm. Partly sunny, with a high near 60. Southwest wind 11 to 17 mph.

    High: 60 °F

    Slight Chance
    Showers

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 53. Breezy.

    Low: 53 °F

    Partly Cloudy
    and Breezy

  • Wednesday

    Wednesday: A 50 percent chance of showers after 2pm. Mostly sunny, with a high near 64. Breezy.

    High: 64 °F

    Mostly Sunny
    and Breezy
    then Chance
    Showers

  • Wednesday Night

    Wednesday Night: Rain likely. Mostly cloudy, with a low around 45. Chance of precipitation is 70%.

    Low: 45 °F

    Rain Likely

  • Thursday

    Thursday: A 50 percent chance of rain. Mostly cloudy, with a high near 49.

    High: 49 °F

    Chance Rain

Detailed Forecast

This Afternoon
Mostly sunny, with a high near 47. Southwest wind 14 to 16 mph.
Tonight
Increasing clouds, with a low around 43. Southwest wind around 18 mph.
Monday
A 20 percent chance of showers after 2pm. Partly sunny, with a high near 56. Southwest wind around 18 mph.
Monday Night
A slight chance of showers before 8pm, then a slight chance of showers after 2am. Mostly cloudy, with a low around 49. Southwest wind 11 to 15 mph. Chance of precipitation is 20%.
Tuesday
A 20 percent chance of showers before 2pm. Partly sunny, with a high near 60. Southwest wind 11 to 17 mph.
Tuesday Night
Partly cloudy, with a low around 53. Breezy.
Wednesday
A 50 percent chance of showers after 2pm. Mostly sunny, with a high near 64. Breezy.
Wednesday Night
Rain likely. Mostly cloudy, with a low around 45. Chance of precipitation is 70%.
Thursday
A 50 percent chance of rain. Mostly cloudy, with a high near 49.
Thursday Night
A 50 percent chance of rain. Cloudy, with a low around 41.
Friday
Rain likely. Cloudy, with a high near 49. Chance of precipitation is 60%.
Friday Night
Rain likely. Cloudy, with a low around 42. Chance of precipitation is 60%.
Saturday
A 40 percent chance of rain. Cloudy, with a high near 48.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.96°N 73.08°W (Elev. 3 ft)
Last Update:
2:25 am EDT Mar 29, 2026
Forecast Valid:
2pm EDT Mar 29, 2026-6pm EDT Apr 4, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

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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