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.

A Few Clouds

73°F

23°C

Humidity 96%
Wind Speed Calm
Barometer 29.99 in (1015.5 mb)
Dewpoint 72°F (22°C)
Visibility 8.00 mi
Last update 28 Aug 12:56 am EDT
Extended Forecast for

Stony Brook NY

  • Overnight

    Overnight: A 20 percent chance of showers and thunderstorms before 2am. Mostly cloudy, with a low around 70. South wind around 7 mph.

    Low: 70 °F

    Slight Chance
    T-storms

  • Friday

    Friday: A 30 percent chance of showers and thunderstorms after 11am. Partly sunny, with a high near 81. West wind 3 to 6 mph.

    High: 81 °F

    Chance
    Showers

  • Friday Night

    Friday Night: A 20 percent chance of showers and thunderstorms before 11pm. Mostly cloudy, with a low around 66. Light and variable wind becoming north 5 to 8 mph after midnight.

    Low: 66 °F

    Slight Chance
    T-storms then
    Mostly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 80. North wind 5 to 7 mph becoming light and variable in the afternoon.

    High: 80 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 65. Light south wind.

    Low: 65 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 83.

    High: 83 °F

    Sunny

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 69.

    Low: 69 °F

    Partly Cloudy

  • Monday

    Monday: A 30 percent chance of showers and thunderstorms after 2pm. Partly sunny, with a high near 83.

    High: 83 °F

    Partly Sunny
    then Chance
    T-storms

  • Monday Night

    Monday Night: A 30 percent chance of showers and thunderstorms before 8pm. Mostly cloudy, with a low around 69.

    Low: 69 °F

    Chance
    T-storms then
    Mostly Cloudy

Detailed Forecast

Overnight
A 20 percent chance of showers and thunderstorms before 2am. Mostly cloudy, with a low around 70. South wind around 7 mph.
Friday
A 30 percent chance of showers and thunderstorms after 11am. Partly sunny, with a high near 81. West wind 3 to 6 mph.
Friday Night
A 20 percent chance of showers and thunderstorms before 11pm. Mostly cloudy, with a low around 66. Light and variable wind becoming north 5 to 8 mph after midnight.
Saturday
Mostly sunny, with a high near 80. North wind 5 to 7 mph becoming light and variable in the afternoon.
Saturday Night
Mostly clear, with a low around 65. Light south wind.
Sunday
Sunny, with a high near 83.
Sunday Night
Partly cloudy, with a low around 69.
Monday
A 30 percent chance of showers and thunderstorms after 2pm. Partly sunny, with a high near 83.
Monday Night
A 30 percent chance of showers and thunderstorms before 8pm. Mostly cloudy, with a low around 69.
Tuesday
A 30 percent chance of showers after 2pm. Partly sunny, with a high near 82.
Tuesday Night
A 50 percent chance of showers. Mostly cloudy, with a low around 68.
Wednesday
A 40 percent chance of showers. Partly sunny, with a high near 81.
Wednesday Night
A 40 percent chance of showers. Mostly cloudy, with a low around 68.
Thursday
Partly sunny, with a high near 81.
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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:
8:06 pm EDT Aug 27, 2026
Forecast Valid:
1am EDT Aug 28, 2026-6pm EDT Sep 3, 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