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

78°F

26°C

Humidity 82%
Wind Speed S 12 G 21 mph
Barometer 29.98 in (1015.0 mb)
Dewpoint 72°F (22°C)
Visibility 10.00 mi
Heat Index80°F (27°C)
Last update 2 Aug 9:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Today

    Today: A 30 percent chance of showers and thunderstorms after 5pm. Mostly cloudy, with a high near 83. South wind 9 to 13 mph.

    High: 83 °F

    Mostly Cloudy
    then Chance
    Showers

  • Tonight

    Tonight: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 8pm. Cloudy, with a low around 71. South wind 8 to 13 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    Low: 71 °F

    Showers
    Likely

  • Monday

    Monday: Showers and possibly a thunderstorm. High near 81. Southwest wind around 14 mph, with gusts as high as 24 mph. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.

    High: 81 °F

    Showers

  • Monday Night

    Monday Night: Showers and thunderstorms likely before 11pm, then a chance of showers between 11pm and 2am. Cloudy, then gradually becoming partly cloudy, with a low around 68. Southwest wind around 7 mph becoming northwest after midnight. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    Low: 68 °F

    Showers
    Likely then
    Chance
    Showers

  • Tuesday

    Tuesday: Mostly sunny, with a high near 83. North wind around 7 mph becoming south in the afternoon.

    High: 83 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 69.

    Low: 69 °F

    Mostly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 83.

    High: 83 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 71.

    Low: 71 °F

    Partly Cloudy

  • Thursday

    Thursday: Mostly sunny, with a high near 85.

    High: 85 °F

    Mostly Sunny

Detailed Forecast

Today
A 30 percent chance of showers and thunderstorms after 5pm. Mostly cloudy, with a high near 83. South wind 9 to 13 mph.
Tonight
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 8pm. Cloudy, with a low around 71. South wind 8 to 13 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Monday
Showers and possibly a thunderstorm. High near 81. Southwest wind around 14 mph, with gusts as high as 24 mph. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.
Monday Night
Showers and thunderstorms likely before 11pm, then a chance of showers between 11pm and 2am. Cloudy, then gradually becoming partly cloudy, with a low around 68. Southwest wind around 7 mph becoming northwest after midnight. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Tuesday
Mostly sunny, with a high near 83. North wind around 7 mph becoming south in the afternoon.
Tuesday Night
Mostly cloudy, with a low around 69.
Wednesday
Mostly sunny, with a high near 83.
Wednesday Night
Partly cloudy, with a low around 71.
Thursday
Mostly sunny, with a high near 85.
Thursday Night
A chance of showers between 8pm and 2am. Partly cloudy, with a low around 72. Chance of precipitation is 40%.
Friday
A 30 percent chance of showers. Mostly sunny, with a high near 85.
Friday Night
A 40 percent chance of showers. Mostly cloudy, with a low around 72.
Saturday
A 30 percent chance of showers. Mostly sunny, with a high near 84.
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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:
7:44 am EDT Aug 2, 2026
Forecast Valid:
10am EDT Aug 2, 2026-6pm EDT Aug 8, 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