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 87%
Wind Speed SW 7 mph
Barometer 30.00 in (1015.8 mb)
Dewpoint 67°F (19°C)
Visibility 10.00 mi
Last update 23 Sep 11:56 pm EDT
Extended Forecast for

Smithtown NY

  • Overnight

    Overnight: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 2am. Patchy fog. Otherwise, mostly cloudy, with a steady temperature around 66. Light southwest wind. Chance of precipitation is 60%.

    Low: 66 °F

    Showers
    Likely and
    Patchy Fog

  • Wednesday

    Wednesday: A chance of showers, with thunderstorms also possible after 2pm. Patchy fog before 10am. Otherwise, partly sunny, with a high near 76. Calm wind becoming southeast around 6 mph in the afternoon. Chance of precipitation is 40%.

    High: 76 °F

    Chance
    Showers and
    Patchy Fog

  • Wednesday Night

    Wednesday Night: Showers and possibly a thunderstorm. Low around 64. East wind around 6 mph. Chance of precipitation is 80%. New rainfall amounts between a quarter and half of an inch possible.

    Low: 64 °F

    Showers

  • Thursday

    Thursday: Showers. High near 74. South wind 6 to 10 mph. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.

    High: 74 °F

    Showers

  • Thursday Night

    Thursday Night: Showers and possibly a thunderstorm before 2am, then showers likely. Low around 64. South wind around 7 mph. Chance of precipitation is 80%. New rainfall amounts between a half and three quarters of an inch possible.

    Low: 64 °F

    Showers

  • Friday

    Friday: Showers likely, mainly before 8am. Mostly cloudy, with a high near 78. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 78 °F

    Showers
    Likely then
    Chance
    Showers

  • Friday Night

    Friday Night: A 30 percent chance of showers. Mostly cloudy, with a low around 61.

    Low: 61 °F

    Chance
    Showers

  • Saturday

    Saturday: A 30 percent chance of showers. Partly sunny, with a high near 76.

    High: 76 °F

    Chance
    Showers

  • Saturday Night

    Saturday Night: A 30 percent chance of showers before 2am. Mostly cloudy, with a low around 62.

    Low: 62 °F

    Chance
    Showers

Detailed Forecast

Overnight
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 2am. Patchy fog. Otherwise, mostly cloudy, with a steady temperature around 66. Light southwest wind. Chance of precipitation is 60%.
Wednesday
A chance of showers, with thunderstorms also possible after 2pm. Patchy fog before 10am. Otherwise, partly sunny, with a high near 76. Calm wind becoming southeast around 6 mph in the afternoon. Chance of precipitation is 40%.
Wednesday Night
Showers and possibly a thunderstorm. Low around 64. East wind around 6 mph. Chance of precipitation is 80%. New rainfall amounts between a quarter and half of an inch possible.
Thursday
Showers. High near 74. South wind 6 to 10 mph. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.
Thursday Night
Showers and possibly a thunderstorm before 2am, then showers likely. Low around 64. South wind around 7 mph. Chance of precipitation is 80%. New rainfall amounts between a half and three quarters of an inch possible.
Friday
Showers likely, mainly before 8am. Mostly cloudy, with a high near 78. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.
Friday Night
A 30 percent chance of showers. Mostly cloudy, with a low around 61.
Saturday
A 30 percent chance of showers. Partly sunny, with a high near 76.
Saturday Night
A 30 percent chance of showers before 2am. Mostly cloudy, with a low around 62.
Sunday
Mostly sunny, with a high near 78.
Sunday Night
Partly cloudy, with a low around 59.
Monday
Mostly sunny, with a high near 76.
Monday Night
Partly cloudy, with a low around 58.
Tuesday
Mostly sunny, with a high near 74.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Smithtown NY
 40.86°N 73.19°W (Elev. 98 ft)
Last Update:
3:57 pm EDT Sep 23, 2025
Forecast Valid:
1am EDT Sep 24, 2025-6pm EDT Sep 30, 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