National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Hazardous Weather Conditions

Current conditions at

Islip, Long Island Mac Arthur Airport (KISP)

Lat: 40.79°NLon: 73.1°WElev: 98ft.

Fair

67°F

19°C

Humidity 81%
Wind Speed SW 3 mph
Barometer 29.98 in (1015.2 mb)
Dewpoint 61°F (16°C)
Visibility 10.00 mi
Last update 20 May 12:56 am EDT
Extended Forecast for

Stony Brook NY

  • Overnight

    Overnight: Mostly clear, with a low around 70. Southwest wind around 9 mph.

    Low: 70 °F

    Mostly Clear

  • Wednesday

    Wednesday: A chance of showers and thunderstorms between 2pm and 5pm, then showers likely and possibly a thunderstorm after 5pm. Increasing clouds, with a high near 89. Southwest wind 9 to 13 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    High: 89 °F

    Sunny then
    Showers
    Likely

  • Wednesday Night

    Wednesday Night: Showers likely and possibly a thunderstorm before 8pm, then a chance of showers. Mostly cloudy, with a low around 59. North wind 5 to 9 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    Low: 59 °F

    Showers
    Likely then
    Chance
    Showers

  • Thursday

    Thursday: A 20 percent chance of showers before 2pm. Mostly cloudy, with a high near 68. North wind 5 to 10 mph becoming east in the afternoon.

    High: 68 °F

    Slight Chance
    Showers

  • Thursday Night

    Thursday Night: Mostly cloudy, with a low around 54. Light and variable wind.

    Low: 54 °F

    Mostly Cloudy

  • Friday

    Friday: Partly sunny, with a high near 70.

    High: 70 °F

    Partly Sunny

  • Friday Night

    Friday Night: Showers likely, mainly after 2am. Mostly cloudy, with a low around 52. Chance of precipitation is 60%.

    Low: 52 °F

    Showers
    Likely

  • Saturday

    Saturday: Showers. High near 63. Chance of precipitation is 80%.

    High: 63 °F

    Showers

  • Saturday Night

    Saturday Night: Showers. Low around 53. Chance of precipitation is 80%.

    Low: 53 °F

    Showers

Detailed Forecast

Overnight
Mostly clear, with a low around 70. Southwest wind around 9 mph.
Wednesday
A chance of showers and thunderstorms between 2pm and 5pm, then showers likely and possibly a thunderstorm after 5pm. Increasing clouds, with a high near 89. Southwest wind 9 to 13 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Wednesday Night
Showers likely and possibly a thunderstorm before 8pm, then a chance of showers. Mostly cloudy, with a low around 59. North wind 5 to 9 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Thursday
A 20 percent chance of showers before 2pm. Mostly cloudy, with a high near 68. North wind 5 to 10 mph becoming east in the afternoon.
Thursday Night
Mostly cloudy, with a low around 54. Light and variable wind.
Friday
Partly sunny, with a high near 70.
Friday Night
Showers likely, mainly after 2am. Mostly cloudy, with a low around 52. Chance of precipitation is 60%.
Saturday
Showers. High near 63. Chance of precipitation is 80%.
Saturday Night
Showers. Low around 53. Chance of precipitation is 80%.
Sunday
Showers likely, mainly before 8am. Cloudy, with a high near 67. Chance of precipitation is 60%.
Sunday Night
A 50 percent chance of showers. Mostly cloudy, with a low around 56.
Memorial Day
A 30 percent chance of showers. Mostly cloudy, with a high near 73.
Monday Night
Mostly cloudy, with a low around 58.
Tuesday
Mostly cloudy, with a high near 76.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Stony Brook NY
 40.92°N 73.15°W (Elev. 36 ft)
Last Update:
2:23 pm EDT May 19, 2026
Forecast Valid:
1am EDT May 20, 2026-6pm EDT May 26, 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