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

75°F

24°C

Humidity 74%
Wind Speed SW 8 mph
Barometer 29.82 in (1009.7 mb)
Dewpoint 66°F (19°C)
Visibility 10.00 mi
Last update 14 Oct 1:56 pm EDT
Extended Forecast for

Stony Brook NY

  • This Afternoon

    This Afternoon: A 20 percent chance of showers before 3pm. Partly sunny, with a high near 77. West wind around 9 mph.

    High: 77 °F

    Slight Chance
    Showers

  • Tonight

    Tonight: Partly cloudy, with a low around 52. North wind around 8 mph, with gusts as high as 20 mph.

    Low: 52 °F

    Partly Cloudy

  • Thursday

    Thursday: Sunny, with a high near 60. North wind 5 to 9 mph.

    High: 60 °F

    Sunny

  • Thursday Night

    Thursday Night: Showers likely, mainly after 5am. Increasing clouds, with a low around 52. Southeast wind 3 to 7 mph. Chance of precipitation is 60%.

    Low: 52 °F

    Mostly Clear
    then Showers
    Likely

  • Friday

    Friday: Showers, with thunderstorms also possible after 5pm. High near 71. Southwest wind 10 to 13 mph, with gusts as high as 24 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    High: 71 °F

    Showers

  • Friday Night

    Friday Night: Showers, mainly between 8pm and 2am. Low around 46. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

    Low: 46 °F

    Showers

  • Saturday

    Saturday: A 30 percent chance of showers before 8am. Partly sunny, with a high near 54.

    High: 54 °F

    Chance
    Showers then
    Mostly Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 40.

    Low: 40 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 55.

    High: 55 °F

    Sunny

Detailed Forecast

This Afternoon
A 20 percent chance of showers before 3pm. Partly sunny, with a high near 77. West wind around 9 mph.
Tonight
Partly cloudy, with a low around 52. North wind around 8 mph, with gusts as high as 20 mph.
Thursday
Sunny, with a high near 60. North wind 5 to 9 mph.
Thursday Night
Showers likely, mainly after 5am. Increasing clouds, with a low around 52. Southeast wind 3 to 7 mph. Chance of precipitation is 60%.
Friday
Showers, with thunderstorms also possible after 5pm. High near 71. Southwest wind 10 to 13 mph, with gusts as high as 24 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Friday Night
Showers, mainly between 8pm and 2am. Low around 46. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.
Saturday
A 30 percent chance of showers before 8am. Partly sunny, with a high near 54.
Saturday Night
Mostly clear, with a low around 40.
Sunday
Sunny, with a high near 55.
Sunday Night
Mostly clear, with a low around 45.
Monday
Sunny, with a high near 60.
Monday Night
Partly cloudy, with a low around 48.
Tuesday
Mostly sunny, with a high near 63.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Stony Brook NY
 40.92°N 73.12°W (Elev. 112 ft)
Last Update:
2:21 pm EDT Oct 14, 2026
Forecast Valid:
2pm EDT Oct 14, 2026-6pm EDT Oct 20, 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