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

62°F

17°C

Humidity 54%
Wind Speed NE 13 mph
Barometer 30.17 in (1021.5 mb)
Dewpoint 45°F (7°C)
Visibility 10.00 mi
Last update 19 Sep 6:56 am EDT
Extended Forecast for

Stony Brook NY

  • Today

    Today: Partly sunny, with a high near 69. East wind 8 to 11 mph.

    High: 69 °F

    Partly Sunny

  • Tonight

    Tonight: Increasing clouds, with a low around 56. Southeast wind around 8 mph.

    Low: 56 °F

    Increasing
    Clouds

  • Sunday

    Sunday: Rain, with thunderstorms also possible after 5pm. High near 71. Southeast wind 8 to 11 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

    Chance Rain
    then Rain

  • Sunday Night

    Sunday Night: Rain and possibly a thunderstorm. Low around 58. South wind 7 to 10 mph becoming northeast after midnight. Chance of precipitation is 80%. New precipitation amounts between three quarters and one inch possible.

    Low: 58 °F

    Rain

  • Monday

    Monday: A 30 percent chance of rain before 8am. Mostly cloudy, with a high near 68. Northeast wind 11 to 15 mph.

    High: 68 °F

    Chance Rain
    then Mostly
    Cloudy

  • Monday Night

    Monday Night: Mostly cloudy, with a low around 55.

    Low: 55 °F

    Mostly Cloudy

  • Tuesday

    Tuesday: A 30 percent chance of showers after 2pm. Mostly cloudy, with a high near 65.

    High: 65 °F

    Mostly Cloudy
    then Chance
    Showers

  • Tuesday Night

    Tuesday Night: A 30 percent chance of showers before 8pm. Mostly cloudy, with a low around 54. Breezy.

    Low: 54 °F

    Breezy.
    Chance
    Showers then
    Mostly Cloudy

  • Wednesday

    Wednesday: Mostly cloudy, with a high near 65. Breezy.

    High: 65 °F

    Mostly Cloudy
    and Breezy

Detailed Forecast

Today
Partly sunny, with a high near 69. East wind 8 to 11 mph.
Tonight
Increasing clouds, with a low around 56. Southeast wind around 8 mph.
Sunday
Rain, with thunderstorms also possible after 5pm. High near 71. Southeast wind 8 to 11 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Sunday Night
Rain and possibly a thunderstorm. Low around 58. South wind 7 to 10 mph becoming northeast after midnight. Chance of precipitation is 80%. New precipitation amounts between three quarters and one inch possible.
Monday
A 30 percent chance of rain before 8am. Mostly cloudy, with a high near 68. Northeast wind 11 to 15 mph.
Monday Night
Mostly cloudy, with a low around 55.
Tuesday
A 30 percent chance of showers after 2pm. Mostly cloudy, with a high near 65.
Tuesday Night
A 30 percent chance of showers before 8pm. Mostly cloudy, with a low around 54. Breezy.
Wednesday
Mostly cloudy, with a high near 65. Breezy.
Wednesday Night
A 30 percent chance of showers. Mostly cloudy, with a low around 54. Breezy.
Thursday
A 30 percent chance of showers. Mostly cloudy, with a high near 65. Breezy.
Thursday Night
A 40 percent chance of showers. Mostly cloudy, with a low around 53. Breezy.
Friday
A 40 percent chance of showers. Mostly cloudy, with a high near 66. Breezy.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Stony Brook NY
 40.92°N 73.15°W (Elev. 36 ft)
Last Update:
7:01 am EDT Sep 19, 2026
Forecast Valid:
7am EDT Sep 19, 2026-6pm EDT Sep 25, 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