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.

Fair

68°F

20°C

Humidity 49%
Wind Speed W 10 mph
Barometer 29.72 in (1006.4 mb)
Dewpoint 48°F (9°C)
Visibility 10.00 mi
Last update 20 Jun 1:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Overnight

    Overnight: Clear, with a low around 66. West wind around 16 mph.

    Low: 66 °F

    Clear

  • Saturday

    Saturday: Sunny, with a high near 79. Breezy, with a west wind 14 to 21 mph.

    High: 79 °F

    Sunny and
    Breezy then
    Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 65. West wind 5 to 9 mph.

    Low: 65 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 79. West wind 5 to 7 mph.

    High: 79 °F

    Sunny

  • Sunday Night

    Sunday Night: A 20 percent chance of showers after 2am. Partly cloudy, with a low around 66. Light and variable wind.

    Low: 66 °F

    Partly Cloudy
    then Slight
    Chance
    Showers

  • Monday

    Monday: Showers, with thunderstorms also possible after 5pm. High near 77. Chance of precipitation is 90%. New rainfall amounts between three quarters and one inch possible.

    High: 77 °F

    Showers
    Likely then
    Showers

  • Monday Night

    Monday Night: Showers and possibly a thunderstorm. Low around 66. Chance of precipitation is 90%.

    Low: 66 °F

    Showers

  • Tuesday

    Tuesday: A 30 percent chance of showers before 8am. Mostly sunny, with a high near 79.

    High: 79 °F

    Chance
    Showers then
    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 66.

    Low: 66 °F

    Mostly Clear

Detailed Forecast

Overnight
Clear, with a low around 66. West wind around 16 mph.
Saturday
Sunny, with a high near 79. Breezy, with a west wind 14 to 21 mph.
Saturday Night
Mostly clear, with a low around 65. West wind 5 to 9 mph.
Sunday
Sunny, with a high near 79. West wind 5 to 7 mph.
Sunday Night
A 20 percent chance of showers after 2am. Partly cloudy, with a low around 66. Light and variable wind.
Monday
Showers, with thunderstorms also possible after 5pm. High near 77. Chance of precipitation is 90%. New rainfall amounts between three quarters and one inch possible.
Monday Night
Showers and possibly a thunderstorm. Low around 66. Chance of precipitation is 90%.
Tuesday
A 30 percent chance of showers before 8am. Mostly sunny, with a high near 79.
Tuesday Night
Mostly clear, with a low around 66.
Wednesday
Sunny, with a high near 82.
Wednesday Night
Mostly clear, with a low around 67.
Thursday
Sunny, with a high near 82.
Thursday Night
Partly cloudy, with a low around 67.
Friday
A 40 percent chance of showers. Partly sunny, with a high near 83.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.95°N 73.05°W (Elev. 151 ft)
Last Update:
2:19 am EDT Jun 20, 2026
Forecast Valid:
2am EDT Jun 20, 2026-6pm EDT Jun 26, 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