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.

Overcast

61°F

16°C

Humidity 78%
Wind Speed N 6 mph
Barometer 30.22 in (1023.2 mb)
Dewpoint 54°F (12°C)
Visibility 10.00 mi
Last update 21 May 2:56 pm EDT
Extended Forecast for

Stony Brook NY

  • This Afternoon

    This Afternoon: A 40 percent chance of rain. Cloudy, with a high near 63. Northeast wind around 6 mph.

    High: 63 °F

    Chance Rain

  • Tonight

    Tonight: A 30 percent chance of rain before 8pm. Cloudy, with a low around 54. Light and variable wind.

    Low: 54 °F

    Chance Rain
    then Mostly
    Cloudy

  • Friday

    Friday: Partly sunny, with a high near 63. Northeast wind 11 to 13 mph.

    High: 63 °F

    Partly Sunny

  • Friday Night

    Friday Night: Mostly cloudy, with a low around 51. East wind around 6 mph.

    Low: 51 °F

    Mostly Cloudy

  • Saturday

    Saturday: Rain, mainly after 2pm. High near 60. East wind 9 to 14 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 60 °F

    Chance Rain
    then Rain

  • Saturday Night

    Saturday Night: Rain. Low around 51. Chance of precipitation is 100%. New precipitation amounts between a half and three quarters of an inch possible.

    Low: 51 °F

    Rain

  • Sunday

    Sunday: Rain. High near 60. Breezy. Chance of precipitation is 100%.

    High: 60 °F

    Rain and
    Breezy

  • Sunday Night

    Sunday Night: Rain likely before 8pm, then a chance of showers after 8pm. Cloudy, with a low around 56. Chance of precipitation is 60%.

    Low: 56 °F

    Rain Likely

  • Memorial Day

    Memorial Day: A 30 percent chance of showers before 2pm. Mostly cloudy, with a high near 70.

    High: 70 °F

    Chance
    Showers

Detailed Forecast

This Afternoon
A 40 percent chance of rain. Cloudy, with a high near 63. Northeast wind around 6 mph.
Tonight
A 30 percent chance of rain before 8pm. Cloudy, with a low around 54. Light and variable wind.
Friday
Partly sunny, with a high near 63. Northeast wind 11 to 13 mph.
Friday Night
Mostly cloudy, with a low around 51. East wind around 6 mph.
Saturday
Rain, mainly after 2pm. High near 60. East wind 9 to 14 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.
Saturday Night
Rain. Low around 51. Chance of precipitation is 100%. New precipitation amounts between a half and three quarters of an inch possible.
Sunday
Rain. High near 60. Breezy. Chance of precipitation is 100%.
Sunday Night
Rain likely before 8pm, then a chance of showers after 8pm. Cloudy, with a low around 56. Chance of precipitation is 60%.
Memorial Day
A 30 percent chance of showers before 2pm. Mostly cloudy, with a high near 70.
Monday Night
A 30 percent chance of showers after 8pm. Cloudy, with a low around 59.
Tuesday
Mostly cloudy, with a high near 78.
Tuesday Night
Mostly cloudy, with a low around 60.
Wednesday
Mostly sunny, with a high near 83.
Wednesday Night
Mostly cloudy, with a low around 60.
Thursday
Mostly sunny, with a high near 79.
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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:
2:25 pm EDT May 21, 2026
Forecast Valid:
3pm EDT May 21, 2026-6pm EDT May 28, 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