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

39°F

4°C

Humidity 93%
Wind Speed NE 16 G 28 mph
Barometer 29.75 in (1007.3 mb)
Dewpoint 37°F (3°C)
Visibility 7.00 mi
Wind Chill30°F (-1°C)
Last update 23 Mar 8:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Today

    Today: Rain, mainly before 11am, then a slight chance of showers after 2pm. Steady temperature around 40. North wind around 10 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 40 °F

    Rain then
    Chance Rain

  • Tonight

    Tonight: Mostly cloudy, then gradually becoming mostly clear, with a low around 31. Wind chill values between 25 and 30. Northwest wind 8 to 10 mph.

    Low: 31 °F

    Decreasing
    Clouds

  • Tuesday

    Tuesday: Sunny, with a high near 45. Wind chill values between 25 and 35 early. North wind 6 to 9 mph becoming west in the afternoon.

    High: 45 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Increasing clouds, with a low around 34. Southwest wind around 7 mph.

    Low: 34 °F

    Increasing
    Clouds

  • Wednesday

    Wednesday: Partly sunny, with a high near 50. Southwest wind 6 to 11 mph.

    High: 50 °F

    Partly Sunny

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 40.

    Low: 40 °F

    Mostly Cloudy

  • Thursday

    Thursday: Mostly cloudy, with a high near 55.

    High: 55 °F

    Mostly Cloudy

  • Thursday Night

    Thursday Night: Rain likely after 2am. Mostly cloudy, with a low around 44. Chance of precipitation is 60%.

    Low: 44 °F

    Mostly Cloudy
    then Rain
    Likely

  • Friday

    Friday: Rain likely, mainly before 8am. Partly sunny, with a high near 53. Chance of precipitation is 60%.

    High: 53 °F

    Rain Likely

Detailed Forecast

Today
Rain, mainly before 11am, then a slight chance of showers after 2pm. Steady temperature around 40. North wind around 10 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.
Tonight
Mostly cloudy, then gradually becoming mostly clear, with a low around 31. Wind chill values between 25 and 30. Northwest wind 8 to 10 mph.
Tuesday
Sunny, with a high near 45. Wind chill values between 25 and 35 early. North wind 6 to 9 mph becoming west in the afternoon.
Tuesday Night
Increasing clouds, with a low around 34. Southwest wind around 7 mph.
Wednesday
Partly sunny, with a high near 50. Southwest wind 6 to 11 mph.
Wednesday Night
Mostly cloudy, with a low around 40.
Thursday
Mostly cloudy, with a high near 55.
Thursday Night
Rain likely after 2am. Mostly cloudy, with a low around 44. Chance of precipitation is 60%.
Friday
Rain likely, mainly before 8am. Partly sunny, with a high near 53. Chance of precipitation is 60%.
Friday Night
Partly cloudy, with a low around 27.
Saturday
Sunny, with a high near 41.
Saturday Night
Mostly clear, with a low around 30.
Sunday
Sunny, with a high near 46.
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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:
2:12 am EDT Mar 23, 2026
Forecast Valid:
9am EDT Mar 23, 2026-6pm EDT Mar 29, 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