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

42°F

6°C

Humidity 82%
Wind Speed E 13 mph
Barometer 30.43 in (1030.6 mb)
Dewpoint 37°F (3°C)
Visibility 10.00 mi
Wind Chill35°F (2°C)
Last update 2 Apr 9:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Today

    Today: A 50 percent chance of showers before 11am. Mostly cloudy, with a high near 43. East wind 15 to 17 mph.

    High: 43 °F

    Chance
    Showers then
    Mostly Cloudy

  • Tonight

    Tonight: A chance of drizzle or light rain, mainly after 2am. Patchy fog. Otherwise, cloudy, with a low around 40. East wind 9 to 16 mph. Chance of precipitation is 30%.

    Low: 40 °F

    Chance Light
    Rain and
    Patchy Fog

  • Friday

    Friday: A chance of drizzle or light rain before 11am. Areas of fog before 11am. Otherwise, cloudy, then gradually becoming mostly sunny, with a high near 55. East wind 5 to 7 mph. Chance of precipitation is 30%.

    High: 55 °F

    Chance Light
    Rain and
    Areas Fog
    then Partly
    Sunny

  • Friday Night

    Friday Night: Mostly cloudy, with a low around 51. Southwest wind 9 to 13 mph.

    Low: 51 °F

    Mostly Cloudy

  • Saturday

    Saturday: A 30 percent chance of showers, mainly after 2pm. Partly sunny, with a high near 59. Northwest wind 5 to 11 mph becoming east in the afternoon.

    High: 59 °F

    Chance
    Showers

  • Saturday Night

    Saturday Night: A chance of showers before 8pm, then a chance of showers after 2am. Mostly cloudy, with a low around 45. Chance of precipitation is 30%.

    Low: 45 °F

    Chance
    Showers

  • Sunday

    Sunday: Showers, mainly after 8am. High near 57. Chance of precipitation is 100%.

    High: 57 °F

    Showers

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 41.

    Low: 41 °F

    Mostly Cloudy

  • Monday

    Monday: Mostly sunny, with a high near 51.

    High: 51 °F

    Mostly Sunny

Detailed Forecast

Today
A 50 percent chance of showers before 11am. Mostly cloudy, with a high near 43. East wind 15 to 17 mph.
Tonight
A chance of drizzle or light rain, mainly after 2am. Patchy fog. Otherwise, cloudy, with a low around 40. East wind 9 to 16 mph. Chance of precipitation is 30%.
Friday
A chance of drizzle or light rain before 11am. Areas of fog before 11am. Otherwise, cloudy, then gradually becoming mostly sunny, with a high near 55. East wind 5 to 7 mph. Chance of precipitation is 30%.
Friday Night
Mostly cloudy, with a low around 51. Southwest wind 9 to 13 mph.
Saturday
A 30 percent chance of showers, mainly after 2pm. Partly sunny, with a high near 59. Northwest wind 5 to 11 mph becoming east in the afternoon.
Saturday Night
A chance of showers before 8pm, then a chance of showers after 2am. Mostly cloudy, with a low around 45. Chance of precipitation is 30%.
Sunday
Showers, mainly after 8am. High near 57. Chance of precipitation is 100%.
Sunday Night
Mostly cloudy, with a low around 41.
Monday
Mostly sunny, with a high near 51.
Monday Night
Partly cloudy, with a low around 40.
Tuesday
Mostly sunny, with a high near 48.
Tuesday Night
Partly cloudy, with a low around 34.
Wednesday
Sunny, with a high near 45.
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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:
2:20 am EDT Apr 2, 2026
Forecast Valid:
10am EDT Apr 2, 2026-6pm EDT Apr 8, 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