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.

Fog/Mist

48°F

9°C

Humidity 93%
Wind Speed N 12 mph
Barometer 29.73 in (1006.8 mb)
Dewpoint 46°F (8°C)
Visibility 5.00 mi
Wind Chill43°F (6°C)
Last update 23 Mar 3:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Overnight

    Overnight: Rain. Steady temperature around 43. Northeast wind 11 to 13 mph. Chance of precipitation is 100%. New precipitation amounts between a tenth and quarter of an inch possible.

    Low: 43 °F

    Rain

  • Monday

    Monday: Rain, mainly before 11am, then a slight chance of showers after 2pm. Temperature falling to around 39 by 10am. North wind 10 to 14 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 43 °F⇓

    Rain then
    Chance Rain

  • Monday Night

    Monday Night: Mostly cloudy, then gradually becoming mostly clear, with a low around 33. Wind chill values between 25 and 30. Northwest wind 14 to 18 mph.

    Low: 33 °F

    Decreasing
    Clouds

  • Tuesday

    Tuesday: Sunny, with a high near 44. Wind chill values between 25 and 35. North wind 6 to 14 mph becoming west in the afternoon.

    High: 44 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Increasing clouds, with a low around 37. Southwest wind around 11 mph.

    Low: 37 °F

    Increasing
    Clouds

  • Wednesday

    Wednesday: Partly sunny, with a high near 48.

    High: 48 °F

    Partly Sunny

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 42.

    Low: 42 °F

    Mostly Cloudy

  • Thursday

    Thursday: Mostly cloudy, with a high near 53.

    High: 53 °F

    Mostly Cloudy

  • Thursday Night

    Thursday Night: Rain likely after 2am. Mostly cloudy, with a low around 46. Chance of precipitation is 60%.

    Low: 46 °F

    Mostly Cloudy
    then Rain
    Likely

Detailed Forecast

Overnight
Rain. Steady temperature around 43. Northeast wind 11 to 13 mph. Chance of precipitation is 100%. New precipitation amounts between a tenth and quarter of an inch possible.
Monday
Rain, mainly before 11am, then a slight chance of showers after 2pm. Temperature falling to around 39 by 10am. North wind 10 to 14 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.
Monday Night
Mostly cloudy, then gradually becoming mostly clear, with a low around 33. Wind chill values between 25 and 30. Northwest wind 14 to 18 mph.
Tuesday
Sunny, with a high near 44. Wind chill values between 25 and 35. North wind 6 to 14 mph becoming west in the afternoon.
Tuesday Night
Increasing clouds, with a low around 37. Southwest wind around 11 mph.
Wednesday
Partly sunny, with a high near 48.
Wednesday Night
Mostly cloudy, with a low around 42.
Thursday
Mostly cloudy, with a high near 53.
Thursday Night
Rain likely after 2am. Mostly cloudy, with a low around 46. Chance of precipitation is 60%.
Friday
Rain likely, mainly before 8am. Partly sunny, with a high near 50. Chance of precipitation is 60%.
Friday Night
Partly cloudy, with a low around 30.
Saturday
Sunny, with a high near 40.
Saturday Night
Mostly clear, with a low around 32.
Sunday
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:
2:12 am EDT Mar 23, 2026
Forecast Valid:
4am 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