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

66°F

19°C

Humidity 52%
Wind Speed NW 10 G 18 mph
Barometer 29.88 in (1011.9 mb)
Dewpoint 48°F (9°C)
Visibility 10.00 mi
Last update 16 Jun 8:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Today

    Today: Sunny, with a high near 76. West wind around 8 mph.

    High: 76 °F

    Sunny

  • Tonight

    Tonight: Partly cloudy, with a low around 61. South wind 5 to 10 mph becoming light after midnight.

    Low: 61 °F

    Partly Cloudy

  • Wednesday

    Wednesday: A slight chance of showers before 2pm, then a slight chance of showers after 5pm. Mostly sunny, with a high near 76. Light south wind increasing to 5 to 9 mph in the morning. Chance of precipitation is 20%.

    High: 76 °F

    Slight Chance
    Showers

  • Wednesday Night

    Wednesday Night: A slight chance of showers before 8pm, then a slight chance of showers after 2am. Mostly cloudy, with a low around 65. South wind 3 to 6 mph. Chance of precipitation is 20%.

    Low: 65 °F

    Mostly Cloudy
    then Slight
    Chance
    Showers

  • Thursday

    Thursday: A slight chance of showers before 8am, then a chance of showers and thunderstorms after 2pm. Mostly cloudy, with a high near 83. South wind 9 to 17 mph. Chance of precipitation is 40%.

    High: 83 °F

    Mostly Cloudy
    then Chance
    Showers

  • Thursday Night

    Thursday Night: A 30 percent chance of showers before 8pm. Partly cloudy, with a low around 71.

    Low: 71 °F

    Chance
    Showers then
    Partly Cloudy

  • Juneteenth

    Juneteenth: Mostly sunny, with a high near 83.

    High: 83 °F

    Mostly Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 68.

    Low: 68 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 85.

    High: 85 °F

    Sunny

Detailed Forecast

Today
Sunny, with a high near 76. West wind around 8 mph.
Tonight
Partly cloudy, with a low around 61. South wind 5 to 10 mph becoming light after midnight.
Wednesday
A slight chance of showers before 2pm, then a slight chance of showers after 5pm. Mostly sunny, with a high near 76. Light south wind increasing to 5 to 9 mph in the morning. Chance of precipitation is 20%.
Wednesday Night
A slight chance of showers before 8pm, then a slight chance of showers after 2am. Mostly cloudy, with a low around 65. South wind 3 to 6 mph. Chance of precipitation is 20%.
Thursday
A slight chance of showers before 8am, then a chance of showers and thunderstorms after 2pm. Mostly cloudy, with a high near 83. South wind 9 to 17 mph. Chance of precipitation is 40%.
Thursday Night
A 30 percent chance of showers before 8pm. Partly cloudy, with a low around 71.
Juneteenth
Mostly sunny, with a high near 83.
Friday Night
Mostly clear, with a low around 68.
Saturday
Sunny, with a high near 85.
Saturday Night
Mostly clear, with a low around 67.
Sunday
Sunny, with a high near 86.
Sunday Night
Partly cloudy, with a low around 68.
Monday
A 40 percent chance of showers. Partly sunny, with a high near 83.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.93°N 73.06°W (Elev. 161 ft)
Last Update:
5:30 am EDT Jun 16, 2026
Forecast Valid:
9am EDT Jun 16, 2026-6pm EDT Jun 22, 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