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

70°F

21°C

Humidity 59%
Wind Speed SE 9 mph
Barometer 30.17 in (1021.5 mb)
Dewpoint 55°F (13°C)
Visibility 10.00 mi
Last update 19 Aug 6:56 pm EDT
Extended Forecast for

Smithtown NY

  • Tonight

    Tonight: Partly cloudy, with a low around 63. East wind 6 to 9 mph.

    Low: 63 °F

    Partly Cloudy

  • Wednesday

    Wednesday: A 50 percent chance of showers, mainly after 11am. Increasing clouds, with a high near 75. East wind 8 to 11 mph.

    High: 75 °F

    Chance
    Showers

  • Wednesday Night

    Wednesday Night: Showers likely and possibly a thunderstorm before 2am, then a chance of showers and thunderstorms after 2am. Mostly cloudy, with a low around 62. East wind 10 to 13 mph. Chance of precipitation is 60%. New rainfall amounts between a quarter and half of an inch possible.

    Low: 62 °F

    Showers
    Likely

  • Thursday

    Thursday: A chance of showers and thunderstorms before 8am, then a slight chance of showers between 8am and 2pm. Partly sunny, with a high near 76. Breezy, with a northeast wind 17 to 20 mph. Chance of precipitation is 30%.

    High: 76 °F

    Chance
    Showers and
    Breezy

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 60. Breezy, with a north wind 18 to 20 mph.

    Low: 60 °F

    Partly Cloudy
    and Breezy
    then Partly
    Cloudy

  • Friday

    Friday: Sunny, with a high near 81.

    High: 81 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 63.

    Low: 63 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 82.

    High: 82 °F

    Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 66.

    Low: 66 °F

    Mostly Clear

Detailed Forecast

Tonight
Partly cloudy, with a low around 63. East wind 6 to 9 mph.
Wednesday
A 50 percent chance of showers, mainly after 11am. Increasing clouds, with a high near 75. East wind 8 to 11 mph.
Wednesday Night
Showers likely and possibly a thunderstorm before 2am, then a chance of showers and thunderstorms after 2am. Mostly cloudy, with a low around 62. East wind 10 to 13 mph. Chance of precipitation is 60%. New rainfall amounts between a quarter and half of an inch possible.
Thursday
A chance of showers and thunderstorms before 8am, then a slight chance of showers between 8am and 2pm. Partly sunny, with a high near 76. Breezy, with a northeast wind 17 to 20 mph. Chance of precipitation is 30%.
Thursday Night
Partly cloudy, with a low around 60. Breezy, with a north wind 18 to 20 mph.
Friday
Sunny, with a high near 81.
Friday Night
Mostly clear, with a low around 63.
Saturday
Sunny, with a high near 82.
Saturday Night
Mostly clear, with a low around 66.
Sunday
A 30 percent chance of showers after 2pm. Partly sunny, with a high near 81.
Sunday Night
A 50 percent chance of showers. Mostly cloudy, with a low around 67.
Monday
A 40 percent chance of showers. Partly sunny, with a high near 82.
Monday Night
Partly cloudy, with a low around 63.
Tuesday
Sunny, with a high near 80.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Smithtown NY
 40.88°N 73.21°W (Elev. 85 ft)
Last Update:
3:14 pm EDT Aug 19, 2025
Forecast Valid:
6pm EDT Aug 19, 2025-6pm EDT Aug 26, 2025
 
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