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.

Fair

51°F

11°C

Humidity 80%
Wind Speed SW 10 mph
Barometer 30.09 in (1019.0 mb)
Dewpoint 45°F (7°C)
Visibility 10.00 mi
Wind Chill47°F (8°C)
Last update 13 May 1:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Overnight

    Overnight: Mostly cloudy, with a low around 52. South wind around 8 mph.

    Low: 52 °F

    Mostly Cloudy

  • Wednesday

    Wednesday: Mostly cloudy, with a high near 68. Breezy, with a south wind 11 to 16 mph increasing to 17 to 22 mph in the afternoon. Winds could gust as high as 34 mph.

    High: 68 °F

    Mostly Cloudy
    then Mostly
    Cloudy and
    Breezy

  • Wednesday Night

    Wednesday Night: Showers, mainly after 2am. Patchy fog after 2am. Low around 55. South wind 9 to 16 mph, with gusts as high as 30 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

    Low: 55 °F

    Chance
    Showers then
    Showers and
    Patchy Fog

  • Thursday

    Thursday: Showers and possibly a thunderstorm. Patchy fog. High near 68. Southeast wind around 6 mph becoming calm in the afternoon. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.

    High: 68 °F

    Showers and
    Patchy Fog

  • Thursday Night

    Thursday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 52. Northwest wind 5 to 7 mph. Chance of precipitation is 50%.

    Low: 52 °F

    Chance
    Showers

  • Friday

    Friday: A 40 percent chance of showers before 2pm. Partly sunny, with a high near 70.

    High: 70 °F

    Chance
    Showers

  • Friday Night

    Friday Night: Partly cloudy, with a low around 55.

    Low: 55 °F

    Partly Cloudy

  • Saturday

    Saturday: Sunny, with a high near 79.

    High: 79 °F

    Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 61.

    Low: 61 °F

    Mostly Clear

Detailed Forecast

Overnight
Mostly cloudy, with a low around 52. South wind around 8 mph.
Wednesday
Mostly cloudy, with a high near 68. Breezy, with a south wind 11 to 16 mph increasing to 17 to 22 mph in the afternoon. Winds could gust as high as 34 mph.
Wednesday Night
Showers, mainly after 2am. Patchy fog after 2am. Low around 55. South wind 9 to 16 mph, with gusts as high as 30 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.
Thursday
Showers and possibly a thunderstorm. Patchy fog. High near 68. Southeast wind around 6 mph becoming calm in the afternoon. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.
Thursday Night
A chance of showers and thunderstorms. Mostly cloudy, with a low around 52. Northwest wind 5 to 7 mph. Chance of precipitation is 50%.
Friday
A 40 percent chance of showers before 2pm. Partly sunny, with a high near 70.
Friday Night
Partly cloudy, with a low around 55.
Saturday
Sunny, with a high near 79.
Saturday Night
Mostly clear, with a low around 61.
Sunday
Sunny, with a high near 85.
Sunday Night
Partly cloudy, with a low around 60.
Monday
Mostly sunny, with a high near 80.
Monday Night
Partly cloudy, with a low around 61.
Tuesday
Mostly sunny, with a high near 85.
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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:
2:36 pm EDT May 12, 2026
Forecast Valid:
2am EDT May 13, 2026-6pm EDT May 19, 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