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.

Partly Cloudy

35°F

2°C

Humidity 42%
Wind Speed N 13 mph
Barometer 30.19 in (1022.3 mb)
Dewpoint 14°F (-10°C)
Visibility 10.00 mi
Wind Chill26°F (-3°C)
Last update 28 Mar 3:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Overnight

    Overnight: A 20 percent chance of snow showers before 5am. Mostly cloudy, with a steady temperature around 33. North wind around 7 mph.

    Low: 33 °F

    Slight Chance
    Snow Showers

  • Saturday

    Saturday: Mostly sunny, with a high near 42. Wind chill values between 25 and 35. Northwest wind 9 to 14 mph, with gusts as high as 26 mph.

    High: 42 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 28. Northwest wind 5 to 10 mph becoming light after midnight. Winds could gust as high as 24 mph.

    Low: 28 °F

    Mostly Clear

  • Sunday

    Sunday: Mostly sunny, with a high near 46. Southwest wind 5 to 15 mph.

    High: 46 °F

    Mostly Sunny

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 40. Southwest wind 10 to 14 mph, with gusts as high as 24 mph.

    Low: 40 °F

    Mostly Cloudy

  • Monday

    Monday: Mostly cloudy, with a high near 59.

    High: 59 °F

    Mostly Cloudy

  • Monday Night

    Monday Night: A 30 percent chance of rain after 2am. Mostly cloudy, with a low around 45.

    Low: 45 °F

    Mostly Cloudy
    then Chance
    Rain

  • Tuesday

    Tuesday: A 30 percent chance of rain before 2pm. Partly sunny, with a high near 62.

    High: 62 °F

    Chance Rain

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 51.

    Low: 51 °F

    Partly Cloudy

Detailed Forecast

Overnight
A 20 percent chance of snow showers before 5am. Mostly cloudy, with a steady temperature around 33. North wind around 7 mph.
Saturday
Mostly sunny, with a high near 42. Wind chill values between 25 and 35. Northwest wind 9 to 14 mph, with gusts as high as 26 mph.
Saturday Night
Mostly clear, with a low around 28. Northwest wind 5 to 10 mph becoming light after midnight. Winds could gust as high as 24 mph.
Sunday
Mostly sunny, with a high near 46. Southwest wind 5 to 15 mph.
Sunday Night
Mostly cloudy, with a low around 40. Southwest wind 10 to 14 mph, with gusts as high as 24 mph.
Monday
Mostly cloudy, with a high near 59.
Monday Night
A 30 percent chance of rain after 2am. Mostly cloudy, with a low around 45.
Tuesday
A 30 percent chance of rain before 2pm. Partly sunny, with a high near 62.
Tuesday Night
Partly cloudy, with a low around 51.
Wednesday
Rain likely after 2pm. Partly sunny, with a high near 64. Chance of precipitation is 60%.
Wednesday Night
Rain likely. Cloudy, with a low around 40. Chance of precipitation is 70%.
Thursday
A 40 percent chance of rain. Cloudy, with a high near 49.
Thursday Night
A chance of rain and snow. Mostly cloudy, with a low around 35. Chance of precipitation is 50%.
Friday
Rain and snow likely. Cloudy, with a high near 44. Chance of precipitation is 60%.
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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:
2:27 am EDT Mar 28, 2026
Forecast Valid:
4am EDT Mar 28, 2026-6pm EDT Apr 3, 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