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.

Overcast

54°F

12°C

Humidity 87%
Wind Speed SW 17 G 30 mph
Barometer 30.15 in (1021.0 mb)
Dewpoint 50°F (10°C)
Visibility 10.00 mi
Wind Chill49°F (9°C)
Last update 13 Apr 8:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Today

    Today: Partly sunny, with a high near 73. Southwest wind 11 to 16 mph, with gusts as high as 29 mph.

    High: 73 °F

    Partly Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 54. West wind 6 to 13 mph.

    Low: 54 °F

    Mostly Clear

  • Tuesday

    Tuesday: Mostly sunny, with a high near 74. South wind 3 to 8 mph.

    High: 74 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: A 20 percent chance of showers before 2am. Mostly cloudy, with a low around 55. Southwest wind 6 to 9 mph.

    Low: 55 °F

    Slight Chance
    Showers

  • Wednesday

    Wednesday: A 30 percent chance of showers after 2pm. Mostly sunny, with a high near 77. Southwest wind 6 to 10 mph.

    High: 77 °F

    Mostly Sunny
    then Chance
    Showers

  • Wednesday Night

    Wednesday Night: A 40 percent chance of showers before 2am. Mostly cloudy, with a low around 56.

    Low: 56 °F

    Chance
    Showers

  • Thursday

    Thursday: Mostly cloudy, with a high near 72.

    High: 72 °F

    Mostly Cloudy

  • Thursday Night

    Thursday Night: Mostly cloudy, with a low around 54.

    Low: 54 °F

    Mostly Cloudy

  • Friday

    Friday: Partly sunny, with a high near 71.

    High: 71 °F

    Partly Sunny

Detailed Forecast

Today
Partly sunny, with a high near 73. Southwest wind 11 to 16 mph, with gusts as high as 29 mph.
Tonight
Mostly clear, with a low around 54. West wind 6 to 13 mph.
Tuesday
Mostly sunny, with a high near 74. South wind 3 to 8 mph.
Tuesday Night
A 20 percent chance of showers before 2am. Mostly cloudy, with a low around 55. Southwest wind 6 to 9 mph.
Wednesday
A 30 percent chance of showers after 2pm. Mostly sunny, with a high near 77. Southwest wind 6 to 10 mph.
Wednesday Night
A 40 percent chance of showers before 2am. Mostly cloudy, with a low around 56.
Thursday
Mostly cloudy, with a high near 72.
Thursday Night
Mostly cloudy, with a low around 54.
Friday
Partly sunny, with a high near 71.
Friday Night
Partly cloudy, with a low around 52.
Saturday
Mostly sunny, with a high near 67.
Saturday Night
A 30 percent chance of showers. Mostly cloudy, with a low around 50.
Sunday
A 40 percent chance of showers. Mostly cloudy, with a high near 65.
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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:
9:09 am EDT Apr 13, 2026
Forecast Valid:
9am EDT Apr 13, 2026-6pm EDT Apr 19, 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