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.

Mostly Cloudy

54°F

12°C

Humidity 72%
Wind Speed SW 15 G 25 mph
Barometer 30.09 in (1018.8 mb)
Dewpoint 45°F (7°C)
Visibility 10.00 mi
Wind Chill50°F (10°C)
Last update 30 Mar 6:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Showers likely, mainly after 5am. Mostly cloudy, with a low around 50. Southwest wind 8 to 13 mph, with gusts as high as 23 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

    Low: 50 °F

    Slight Chance
    Showers then
    Showers
    Likely

  • Tuesday

    Tuesday: Showers likely, mainly before 8am. Partly sunny, with a high near 64. Southwest wind 10 to 14 mph, with gusts as high as 24 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

    High: 64 °F

    Showers
    Likely then
    Chance
    Showers

  • Tuesday Night

    Tuesday Night: A 20 percent chance of showers after 2am. Partly cloudy, with a low around 52. South wind around 14 mph.

    Low: 52 °F

    Partly Cloudy
    then Slight
    Chance
    Showers

  • Wednesday

    Wednesday: A chance of showers, then showers likely and possibly a thunderstorm after 2pm. Partly sunny, with a high near 63. Southwest wind 11 to 14 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    High: 63 °F

    Chance
    Showers then
    Showers
    Likely

  • Wednesday Night

    Wednesday Night: Showers likely and possibly a thunderstorm. Cloudy, with a low around 43. Northeast wind 6 to 8 mph. Chance of precipitation is 70%. New precipitation amounts between a quarter and half of an inch possible.

    Low: 43 °F

    Showers
    Likely

  • Thursday

    Thursday: A 30 percent chance of showers before 2pm. Cloudy, with a high near 50.

    High: 50 °F

    Chance
    Showers

  • Thursday Night

    Thursday Night: A chance of showers between 8pm and 2am. Cloudy, with a low around 42. Chance of precipitation is 30%.

    Low: 42 °F

    Chance
    Showers

  • Friday

    Friday: Mostly cloudy, with a high near 60.

    High: 60 °F

    Mostly Cloudy

  • Friday Night

    Friday Night: A 30 percent chance of showers before 2am. Mostly cloudy, with a low around 50.

    Low: 50 °F

    Chance
    Showers

Detailed Forecast

Tonight
Showers likely, mainly after 5am. Mostly cloudy, with a low around 50. Southwest wind 8 to 13 mph, with gusts as high as 23 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Tuesday
Showers likely, mainly before 8am. Partly sunny, with a high near 64. Southwest wind 10 to 14 mph, with gusts as high as 24 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Tuesday Night
A 20 percent chance of showers after 2am. Partly cloudy, with a low around 52. South wind around 14 mph.
Wednesday
A chance of showers, then showers likely and possibly a thunderstorm after 2pm. Partly sunny, with a high near 63. Southwest wind 11 to 14 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Wednesday Night
Showers likely and possibly a thunderstorm. Cloudy, with a low around 43. Northeast wind 6 to 8 mph. Chance of precipitation is 70%. New precipitation amounts between a quarter and half of an inch possible.
Thursday
A 30 percent chance of showers before 2pm. Cloudy, with a high near 50.
Thursday Night
A chance of showers between 8pm and 2am. Cloudy, with a low around 42. Chance of precipitation is 30%.
Friday
Mostly cloudy, with a high near 60.
Friday Night
A 30 percent chance of showers before 2am. Mostly cloudy, with a low around 50.
Saturday
Mostly cloudy, with a high near 63.
Saturday Night
A 40 percent chance of showers. Mostly cloudy, with a low around 47.
Sunday
A 50 percent chance of showers. Mostly cloudy, with a high near 61.
Sunday Night
A 50 percent chance of showers. Mostly cloudy, with a low around 43.
Monday
A 30 percent chance of showers. Partly sunny, with a high near 54.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.93°N 73.06°W (Elev. 161 ft)
Last Update:
5:53 pm EDT Mar 30, 2026
Forecast Valid:
7pm EDT Mar 30, 2026-6pm EDT Apr 6, 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