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

67°F

19°C

Humidity 79%
Wind Speed E 13 mph
Barometer 30.15 in (1020.8 mb)
Dewpoint 60°F (16°C)
Visibility 10.00 mi
Last update 16 Jun 11:56 am EDT
Extended Forecast for

Port Jefferson NY

  • This Afternoon

    This Afternoon: Mostly cloudy, with a high near 65. East wind around 11 mph.

    High: 65 °F

    Mostly Cloudy

  • Tonight

    Tonight: A 20 percent chance of light rain. Cloudy, with a low around 62. East wind 5 to 9 mph.

    Low: 62 °F

    Slight Chance
    Light Rain

  • Tuesday

    Tuesday: A 20 percent chance of showers. Cloudy, with a high near 67. East wind around 8 mph.

    High: 67 °F

    Slight Chance
    Showers

  • Tuesday Night

    Tuesday Night: A 50 percent chance of showers. Cloudy, with a low around 64. Southeast wind around 6 mph.

    Low: 64 °F

    Chance
    Showers

  • Wednesday

    Wednesday: A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 76. South wind around 6 mph.

    High: 76 °F

    Chance
    Showers then
    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A chance of thunderstorms before 8pm. Partly cloudy, with a low around 69. Chance of precipitation is 30%.

    Low: 69 °F

    Chance
    T-storms then
    Partly Cloudy

  • Juneteenth

    Juneteenth: A 30 percent chance of showers after 2pm. Partly sunny, with a high near 83.

    High: 83 °F

    Partly Sunny
    then Chance
    Showers

  • Thursday Night

    Thursday Night: A 30 percent chance of showers before 8pm. Partly cloudy, with a low around 67.

    Low: 67 °F

    Chance
    Showers then
    Partly Cloudy

  • Friday

    Friday: Sunny, with a high near 77.

    High: 77 °F

    Sunny

Detailed Forecast

This Afternoon
Mostly cloudy, with a high near 65. East wind around 11 mph.
Tonight
A 20 percent chance of light rain. Cloudy, with a low around 62. East wind 5 to 9 mph.
Tuesday
A 20 percent chance of showers. Cloudy, with a high near 67. East wind around 8 mph.
Tuesday Night
A 50 percent chance of showers. Cloudy, with a low around 64. Southeast wind around 6 mph.
Wednesday
A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 76. South wind around 6 mph.
Wednesday Night
A chance of thunderstorms before 8pm. Partly cloudy, with a low around 69. Chance of precipitation is 30%.
Juneteenth
A 30 percent chance of showers after 2pm. Partly sunny, with a high near 83.
Thursday Night
A 30 percent chance of showers before 8pm. Partly cloudy, with a low around 67.
Friday
Sunny, with a high near 77.
Friday Night
Mostly clear, with a low around 64.
Saturday
Sunny, with a high near 77.
Saturday Night
Mostly cloudy, with a low around 67.
Sunday
Partly 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:
11:11 am EDT Jun 16, 2025
Forecast Valid:
12pm EDT Jun 16, 2025-6pm EDT Jun 22, 2025
 
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