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.

A Few Clouds and Breezy

34°F

1°C

Humidity 54%
Wind Speed NW 21 G 36 mph
Barometer 29.92 in (1013.3 mb)
Dewpoint 19°F (-7°C)
Visibility 10.00 mi
Wind Chill22°F (-6°C)
Last update 11 Jan 11:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Overnight

    Overnight: Mostly clear, with a low around 32. Wind chill values between 20 and 25. Windy, with a west wind 26 to 30 mph.

    Low: 32 °F

    Mostly Clear
    and Windy

  • Monday

    Monday: Mostly sunny, with a high near 40. Wind chill values between 20 and 30. Breezy, with a southwest wind 15 to 22 mph.

    High: 40 °F

    Sunny and
    Breezy then
    Mostly Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 35. Southwest wind 11 to 15 mph.

    Low: 35 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Sunny, with a high near 43. West wind around 10 mph.

    High: 43 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 40. South wind 11 to 15 mph.

    Low: 40 °F

    Mostly Cloudy

  • Wednesday

    Wednesday: A 30 percent chance of rain before 1pm. Mostly cloudy, with a high near 45.

    High: 45 °F

    Chance Rain

  • Wednesday Night

    Wednesday Night: A 40 percent chance of rain after 1am. Cloudy, with a low around 37.

    Low: 37 °F

    Cloudy then
    Chance Rain

  • Thursday

    Thursday: A 40 percent chance of rain. Mostly cloudy, with a high near 41.

    High: 41 °F

    Chance Rain

  • Thursday Night

    Thursday Night: A chance of rain and snow before 1am, then a chance of snow. Mostly cloudy, with a low around 26. Blustery. Chance of precipitation is 40%.

    Low: 26 °F

    Chance
    Rain/Snow and
    Blustery

Detailed Forecast

Overnight
Mostly clear, with a low around 32. Wind chill values between 20 and 25. Windy, with a west wind 26 to 30 mph.
Monday
Mostly sunny, with a high near 40. Wind chill values between 20 and 30. Breezy, with a southwest wind 15 to 22 mph.
Monday Night
Partly cloudy, with a low around 35. Southwest wind 11 to 15 mph.
Tuesday
Sunny, with a high near 43. West wind around 10 mph.
Tuesday Night
Mostly cloudy, with a low around 40. South wind 11 to 15 mph.
Wednesday
A 30 percent chance of rain before 1pm. Mostly cloudy, with a high near 45.
Wednesday Night
A 40 percent chance of rain after 1am. Cloudy, with a low around 37.
Thursday
A 40 percent chance of rain. Mostly cloudy, with a high near 41.
Thursday Night
A chance of rain and snow before 1am, then a chance of snow. Mostly cloudy, with a low around 26. Blustery. Chance of precipitation is 40%.
Friday
Partly sunny, with a high near 34. Breezy.
Friday Night
Partly cloudy, with a low around 28.
Saturday
Mostly sunny, with a high near 37.
Saturday Night
Mostly cloudy, with a low around 31.
Sunday
A chance of rain and snow. Partly sunny, with a high near 36. Chance of precipitation is 40%.
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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:
1:42 pm EST Jan 11, 2026
Forecast Valid:
12am EST Jan 12, 2026-6pm EST Jan 18, 2026
 
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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