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.

Light Rain

62°F

17°C

Humidity 75%
Wind Speed E 9 mph
Barometer 30.36 in (1028.0 mb)
Dewpoint 54°F (12°C)
Visibility 10.00 mi
Last update 11 Oct 9:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Today

    Today: Rain, mainly after noon. High near 64. East wind 11 to 13 mph. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.

    High: 64 °F

    Chance Rain
    then Rain

  • Tonight

    Tonight: Rain and possibly a thunderstorm before 2am, then a chance of rain and thunderstorms, mainly between 2am and 5am. Low around 57. East wind 15 to 18 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.

    Low: 57 °F

    Rain then
    Rain Likely

  • Columbus Day

    Columbus Day: A 30 percent chance of showers before 11am. Cloudy through mid morning, then gradual clearing, with a high near 68. North wind 7 to 15 mph.

    High: 68 °F

    Chance
    Showers then
    Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 57. Northwest wind 3 to 6 mph.

    Low: 57 °F

    Mostly Clear

  • Tuesday

    Tuesday: Mostly sunny, with a high near 67. East wind 5 to 9 mph becoming south in the afternoon.

    High: 67 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a steady temperature around 64.

    Low: 64 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Sunny, with a high near 71.

    High: 71 °F

    Sunny

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 53.

    Low: 53 °F

    Mostly Clear

  • Thursday

    Thursday: Mostly sunny, with a high near 63.

    High: 63 °F

    Mostly Sunny

Detailed Forecast

Today
Rain, mainly after noon. High near 64. East wind 11 to 13 mph. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.
Tonight
Rain and possibly a thunderstorm before 2am, then a chance of rain and thunderstorms, mainly between 2am and 5am. Low around 57. East wind 15 to 18 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.
Columbus Day
A 30 percent chance of showers before 11am. Cloudy through mid morning, then gradual clearing, with a high near 68. North wind 7 to 15 mph.
Monday Night
Mostly clear, with a low around 57. Northwest wind 3 to 6 mph.
Tuesday
Mostly sunny, with a high near 67. East wind 5 to 9 mph becoming south in the afternoon.
Tuesday Night
Partly cloudy, with a steady temperature around 64.
Wednesday
Sunny, with a high near 71.
Wednesday Night
Mostly clear, with a low around 53.
Thursday
Mostly sunny, with a high near 63.
Thursday Night
Partly cloudy, with a low around 51.
Friday
A 50 percent chance of showers. Mostly cloudy, with a high near 65.
Friday Night
A 50 percent chance of showers. Mostly cloudy, with a low around 52. Breezy.
Saturday
A 30 percent chance of showers. Partly sunny, with a high near 60. Breezy.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.95°N 73.05°W (Elev. 151 ft)
Last Update:
9:50 am EDT Oct 11, 2026
Forecast Valid:
10am EDT Oct 11, 2026-6pm EDT Oct 17, 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