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

64°F

18°C

Humidity 84%
Wind Speed Calm
Barometer 30.21 in (1023.0 mb)
Dewpoint 59°F (15°C)
Visibility 10.00 mi
Last update 4 Oct 10:56 pm EDT
Extended Forecast for

Smithtown NY

  • Tonight

    Tonight: Patchy fog after 1am. Otherwise, mostly clear, with a low around 58. Calm wind.

    Low: 58 °F

    Patchy Fog

  • Sunday

    Sunday: Patchy fog before 10am. Otherwise, sunny, with a high near 81. Calm wind becoming south around 5 mph in the afternoon.

    High: 81 °F

    Patchy Fog
    then Sunny

  • Sunday Night

    Sunday Night: Patchy fog after 4am. Otherwise, clear, with a low around 58. South wind 3 to 5 mph.

    Low: 58 °F

    Clear then
    Patchy Fog

  • Monday

    Monday: Patchy fog before 8am. Otherwise, sunny, with a high near 78. Calm wind becoming south 5 to 8 mph in the afternoon.

    High: 78 °F

    Patchy Fog
    then Sunny

  • Monday Night

    Monday Night: Patchy fog after 2am. Otherwise, mostly clear, with a low around 60. Southwest wind around 7 mph.

    Low: 60 °F

    Mostly Clear
    then Patchy
    Fog

  • Tuesday

    Tuesday: Patchy fog before 8am. Otherwise, mostly sunny, with a high near 77.

    High: 77 °F

    Patchy Fog
    then Partly
    Sunny

  • Tuesday Night

    Tuesday Night: Showers likely, mainly after 2am. Mostly cloudy, with a low around 59. Chance of precipitation is 70%.

    Low: 59 °F

    Chance
    Showers then
    Showers
    Likely

  • Wednesday

    Wednesday: Showers likely, mainly before 2pm. Mostly cloudy, with a high near 71. Chance of precipitation is 60%.

    High: 71 °F

    Showers
    Likely

  • Wednesday Night

    Wednesday Night: A 30 percent chance of showers before 8pm. Partly cloudy, with a low around 49.

    Low: 49 °F

    Chance
    Showers then
    Mostly Clear

Detailed Forecast

Tonight
Patchy fog after 1am. Otherwise, mostly clear, with a low around 58. Calm wind.
Sunday
Patchy fog before 10am. Otherwise, sunny, with a high near 81. Calm wind becoming south around 5 mph in the afternoon.
Sunday Night
Patchy fog after 4am. Otherwise, clear, with a low around 58. South wind 3 to 5 mph.
Monday
Patchy fog before 8am. Otherwise, sunny, with a high near 78. Calm wind becoming south 5 to 8 mph in the afternoon.
Monday Night
Patchy fog after 2am. Otherwise, mostly clear, with a low around 60. Southwest wind around 7 mph.
Tuesday
Patchy fog before 8am. Otherwise, mostly sunny, with a high near 77.
Tuesday Night
Showers likely, mainly after 2am. Mostly cloudy, with a low around 59. Chance of precipitation is 70%.
Wednesday
Showers likely, mainly before 2pm. Mostly cloudy, with a high near 71. Chance of precipitation is 60%.
Wednesday Night
A 30 percent chance of showers before 8pm. Partly cloudy, with a low around 49.
Thursday
Sunny, with a high near 64.
Thursday Night
Mostly clear, with a low around 49.
Friday
Mostly sunny, with a high near 66.
Friday Night
Partly cloudy, with a low around 53.
Saturday
Mostly sunny, with a high near 71.
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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:
2:02 pm EDT Oct 4, 2025
Forecast Valid:
11pm EDT Oct 4, 2025-6pm EDT Oct 11, 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