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.

Fair

53°F

12°C

Humidity 74%
Wind Speed W 5 mph
Barometer 30.03 in (1016.7 mb)
Dewpoint 45°F (7°C)
Visibility 10.00 mi
Wind Chill52°F (11°C)
Last update 9 Oct 12:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Overnight

    Overnight: Clear, with a low around 53. West wind around 5 mph.

    Low: 53 °F

    Clear

  • Friday

    Friday: Sunny, with a high near 69. West wind 6 to 15 mph, with gusts as high as 26 mph.

    High: 69 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 52. West wind around 6 mph.

    Low: 52 °F

    Mostly Clear

  • Saturday

    Saturday: Mostly sunny, with a high near 66. North wind around 5 mph becoming light and variable in the afternoon.

    High: 66 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Mostly cloudy, with a low around 57. South wind around 5 mph becoming calm in the evening.

    Low: 57 °F

    Mostly Cloudy

  • Sunday

    Sunday: A 50 percent chance of showers after 2pm. Mostly cloudy, with a high near 67.

    High: 67 °F

    Mostly Cloudy
    then Chance
    Showers

  • Sunday Night

    Sunday Night: Showers, mainly after 8pm. Low around 62. Chance of precipitation is 90%.

    Low: 62 °F

    Showers

  • Columbus Day

    Columbus Day: A 50 percent chance of showers before 2pm. Mostly cloudy, with a high near 69.

    High: 69 °F

    Chance
    Showers

  • Monday Night

    Monday Night: Mostly cloudy, with a low around 61.

    Low: 61 °F

    Mostly Cloudy

Detailed Forecast

Overnight
Clear, with a low around 53. West wind around 5 mph.
Friday
Sunny, with a high near 69. West wind 6 to 15 mph, with gusts as high as 26 mph.
Friday Night
Mostly clear, with a low around 52. West wind around 6 mph.
Saturday
Mostly sunny, with a high near 66. North wind around 5 mph becoming light and variable in the afternoon.
Saturday Night
Mostly cloudy, with a low around 57. South wind around 5 mph becoming calm in the evening.
Sunday
A 50 percent chance of showers after 2pm. Mostly cloudy, with a high near 67.
Sunday Night
Showers, mainly after 8pm. Low around 62. Chance of precipitation is 90%.
Columbus Day
A 50 percent chance of showers before 2pm. Mostly cloudy, with a high near 69.
Monday Night
Mostly cloudy, with a low around 61.
Tuesday
Mostly sunny, with a high near 70.
Tuesday Night
A 30 percent chance of showers. Mostly cloudy, with a low around 56.
Wednesday
Mostly sunny, with a high near 63.
Wednesday Night
Partly cloudy, with a low around 52.
Thursday
Mostly sunny, with a high near 61.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.95°N 73.05°W (Elev. 151 ft)
Last Update:
7:47 pm EDT Oct 8, 2026
Forecast Valid:
1am EDT Oct 9, 2026-6pm EDT Oct 15, 2026
 
Forecast Discussion
 
Get as KML Get as XML

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