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

71°F

22°C

Humidity 84%
Wind Speed SE 6 mph
Barometer 30.07 in (1018.2 mb)
Dewpoint 66°F (19°C)
Visibility 10.00 mi
Last update 26 Aug 9:56 pm EDT
Extended Forecast for

Smithtown NY

  • Tonight

    Tonight: Mostly cloudy, with a low around 68. South wind around 6 mph.

    Low: 68 °F

    Mostly Cloudy

  • Thursday

    Thursday: A 40 percent chance of showers and thunderstorms after 11am. Partly sunny, with a high near 81. South wind 7 to 14 mph.

    High: 81 °F

    Chance
    Showers

  • Thursday Night

    Thursday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 68. South wind 5 to 9 mph becoming calm after midnight. Chance of precipitation is 50%.

    Low: 68 °F

    Chance
    Showers

  • Friday

    Friday: A slight chance of showers before 8am, then a slight chance of showers after 2pm. Cloudy, then gradually becoming mostly sunny, with a high near 83. Calm wind becoming west around 5 mph in the afternoon. Chance of precipitation is 20%.

    High: 83 °F

    Partly Sunny
    then Slight
    Chance
    Showers

  • Friday Night

    Friday Night: Partly cloudy, with a low around 64. Light and variable wind becoming north around 6 mph after midnight.

    Low: 64 °F

    Partly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 79.

    High: 79 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 64.

    Low: 64 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 81.

    High: 81 °F

    Sunny

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 68.

    Low: 68 °F

    Partly Cloudy

Detailed Forecast

Tonight
Mostly cloudy, with a low around 68. South wind around 6 mph.
Thursday
A 40 percent chance of showers and thunderstorms after 11am. Partly sunny, with a high near 81. South wind 7 to 14 mph.
Thursday Night
A chance of showers and thunderstorms. Mostly cloudy, with a low around 68. South wind 5 to 9 mph becoming calm after midnight. Chance of precipitation is 50%.
Friday
A slight chance of showers before 8am, then a slight chance of showers after 2pm. Cloudy, then gradually becoming mostly sunny, with a high near 83. Calm wind becoming west around 5 mph in the afternoon. Chance of precipitation is 20%.
Friday Night
Partly cloudy, with a low around 64. Light and variable wind becoming north around 6 mph after midnight.
Saturday
Mostly sunny, with a high near 79.
Saturday Night
Mostly clear, with a low around 64.
Sunday
Sunny, with a high near 81.
Sunday Night
Partly cloudy, with a low around 68.
Monday
Mostly sunny, with a high near 83.
Monday Night
Partly cloudy, with a low around 69.
Tuesday
Partly sunny, with a high near 83.
Tuesday Night
A 30 percent chance of showers. Mostly cloudy, with a low around 68.
Wednesday
A 30 percent chance of showers. Partly sunny, with a high near 83.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Smithtown NY
 40.86°N 73.19°W (Elev. 98 ft)
Last Update:
2:53 pm EDT Aug 26, 2026
Forecast Valid:
10pm EDT Aug 26, 2026-6pm EDT Sep 2, 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