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

78°F

26°C

Humidity 43%
Wind Speed NW 12 G 21 mph
Barometer 29.95 in (1014.1 mb)
Dewpoint 54°F (12°C)
Visibility 10.00 mi
Heat Index79°F (26°C)
Last update 24 Jun 11:56 am EDT
Extended Forecast for

Stony Brook NY

  • This Afternoon

    This Afternoon: Sunny, with a high near 81. West wind around 10 mph.

    High: 81 °F

    Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 63. West wind 3 to 6 mph.

    Low: 63 °F

    Mostly Clear

  • Thursday

    Thursday: Mostly sunny, with a high near 81. Calm wind becoming south 5 to 9 mph in the afternoon.

    High: 81 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: A slight chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 2am. Mostly cloudy, with a low around 66. South wind 8 to 10 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    Low: 66 °F

    Slight Chance
    T-storms then
    Showers
    Likely

  • Friday

    Friday: Showers likely, mainly before 8am. Partly sunny, with a high near 79. Southwest wind around 8 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

    High: 79 °F

    Showers
    Likely then
    Slight Chance
    Showers

  • Friday Night

    Friday Night: Showers likely, mainly after 2am. Mostly cloudy, with a low around 67. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

    Low: 67 °F

    Chance
    Showers then
    Showers
    Likely

  • Saturday

    Saturday: Showers likely, mainly before 8am. Mostly cloudy, with a high near 80. Chance of precipitation is 60%.

    High: 80 °F

    Showers
    Likely

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 67.

    Low: 67 °F

    Partly Cloudy

  • Sunday

    Sunday: Sunny, with a high near 83.

    High: 83 °F

    Sunny

Detailed Forecast

This Afternoon
Sunny, with a high near 81. West wind around 10 mph.
Tonight
Mostly clear, with a low around 63. West wind 3 to 6 mph.
Thursday
Mostly sunny, with a high near 81. Calm wind becoming south 5 to 9 mph in the afternoon.
Thursday Night
A slight chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 2am. Mostly cloudy, with a low around 66. South wind 8 to 10 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Friday
Showers likely, mainly before 8am. Partly sunny, with a high near 79. Southwest wind around 8 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Friday Night
Showers likely, mainly after 2am. Mostly cloudy, with a low around 67. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.
Saturday
Showers likely, mainly before 8am. Mostly cloudy, with a high near 80. Chance of precipitation is 60%.
Saturday Night
Partly cloudy, with a low around 67.
Sunday
Sunny, with a high near 83.
Sunday Night
Mostly clear, with a low around 67.
Monday
Sunny, with a high near 84.
Monday Night
Partly cloudy, with a low around 70.
Tuesday
Mostly sunny, with a high near 85.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Stony Brook NY
 40.92°N 73.12°W (Elev. 112 ft)
Last Update:
7:00 am EDT Jun 24, 2026
Forecast Valid:
12pm EDT Jun 24, 2026-6pm EDT Jun 30, 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