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.

Light Rain

43°F

6°C

Humidity 86%
Wind Speed N 5 mph
Barometer 30.10 in (1019.2 mb)
Dewpoint 39°F (4°C)
Visibility 10.00 mi
Wind Chill40°F (4°C)
Last update 7 Apr 2:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Overnight

    Overnight: A 30 percent chance of showers. Mostly cloudy, with a low around 39. Southeast wind around 5 mph.

    Low: 39 °F

    Chance
    Showers

  • Tuesday

    Tuesday: A 30 percent chance of showers before 8am. Mostly sunny, with a high near 51. Breezy, with a west wind 11 to 21 mph, with gusts as high as 32 mph.

    High: 51 °F

    Chance
    Showers then
    Mostly Sunny
    and Breezy

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 28. Wind chill values between 20 and 25. North wind 11 to 17 mph.

    Low: 28 °F

    Mostly Clear

  • Wednesday

    Wednesday: Sunny, with a high near 46. Wind chill values between 20 and 30 early. North wind 8 to 10 mph becoming southeast in the afternoon.

    High: 46 °F

    Sunny

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 31. South wind 5 to 7 mph becoming calm after midnight.

    Low: 31 °F

    Mostly Clear

  • Thursday

    Thursday: Mostly sunny, with a high near 51.

    High: 51 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 38.

    Low: 38 °F

    Partly Cloudy

  • Friday

    Friday: Mostly sunny, with a high near 58.

    High: 58 °F

    Mostly Sunny

  • Friday Night

    Friday Night: Partly cloudy, with a low around 45.

    Low: 45 °F

    Partly Cloudy

Detailed Forecast

Overnight
A 30 percent chance of showers. Mostly cloudy, with a low around 39. Southeast wind around 5 mph.
Tuesday
A 30 percent chance of showers before 8am. Mostly sunny, with a high near 51. Breezy, with a west wind 11 to 21 mph, with gusts as high as 32 mph.
Tuesday Night
Mostly clear, with a low around 28. Wind chill values between 20 and 25. North wind 11 to 17 mph.
Wednesday
Sunny, with a high near 46. Wind chill values between 20 and 30 early. North wind 8 to 10 mph becoming southeast in the afternoon.
Wednesday Night
Mostly clear, with a low around 31. South wind 5 to 7 mph becoming calm after midnight.
Thursday
Mostly sunny, with a high near 51.
Thursday Night
Partly cloudy, with a low around 38.
Friday
Mostly sunny, with a high near 58.
Friday Night
Partly cloudy, with a low around 45.
Saturday
Mostly sunny, with a high near 64.
Saturday Night
Mostly clear, with a low around 43.
Sunday
Sunny, with a high near 58.
Sunday Night
Mostly cloudy, with a low around 46.
Monday
Partly sunny, with a high near 65.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.93°N 73.06°W (Elev. 161 ft)
Last Update:
3:08 am EDT Apr 7, 2026
Forecast Valid:
3am EDT Apr 7, 2026-6pm EDT Apr 13, 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