National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Hazardous Weather Conditions

Current conditions at

Islip, Long Island Mac Arthur Airport (KISP)

Lat: 40.79°NLon: 73.1°WElev: 98ft.

Mostly Cloudy

73°F

23°C

Humidity 64%
Wind Speed S 12 G 21 mph
Barometer 29.83 in (1010.0 mb)
Dewpoint 60°F (16°C)
Visibility 10.00 mi
Last update 17 Jun 3:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Mostly cloudy, with a low around 64. South wind 9 to 11 mph.

    Low: 64 °F

    Mostly Cloudy

  • Thursday

    Thursday: A chance of showers, with thunderstorms also possible after 2pm. Mostly cloudy, with a high near 81. Breezy, with a south wind 17 to 23 mph. Chance of precipitation is 50%.

    High: 81 °F

    Chance
    Showers and
    Breezy

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 68. Southwest wind 14 to 16 mph.

    Low: 68 °F

    Partly Cloudy

  • Juneteenth

    Juneteenth: Mostly sunny, with a high near 80. West wind 13 to 15 mph.

    High: 80 °F

    Mostly Sunny

  • Friday Night

    Friday Night: Clear, with a low around 66. West wind 13 to 18 mph.

    Low: 66 °F

    Clear

  • Saturday

    Saturday: Sunny, with a high near 79. Breezy.

    High: 79 °F

    Sunny and
    Breezy then
    Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 63.

    Low: 63 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 80.

    High: 80 °F

    Sunny

  • Sunday Night

    Sunday Night: A 40 percent chance of showers after 2am. Mostly cloudy, with a low around 65.

    Low: 65 °F

    Partly Cloudy
    then Chance
    Showers

Detailed Forecast

Tonight
Mostly cloudy, with a low around 64. South wind 9 to 11 mph.
Thursday
A chance of showers, with thunderstorms also possible after 2pm. Mostly cloudy, with a high near 81. Breezy, with a south wind 17 to 23 mph. Chance of precipitation is 50%.
Thursday Night
Partly cloudy, with a low around 68. Southwest wind 14 to 16 mph.
Juneteenth
Mostly sunny, with a high near 80. West wind 13 to 15 mph.
Friday Night
Clear, with a low around 66. West wind 13 to 18 mph.
Saturday
Sunny, with a high near 79. Breezy.
Saturday Night
Mostly clear, with a low around 63.
Sunday
Sunny, with a high near 80.
Sunday Night
A 40 percent chance of showers after 2am. Mostly cloudy, with a low around 65.
Monday
Showers, mainly after 8am. High near 78. Chance of precipitation is 80%.
Monday Night
Showers. Low around 64. Chance of precipitation is 80%.
Tuesday
Mostly sunny, with a high near 80.
Tuesday Night
Partly cloudy, with a low around 65.
Wednesday
Sunny, with a high near 81.
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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:
2:20 pm EDT Jun 17, 2026
Forecast Valid:
4pm EDT Jun 17, 2026-6pm EDT Jun 24, 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