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

64°F

18°C

Humidity 90%
Wind Speed NE 5 mph
Barometer 30.05 in (1017.6 mb)
Dewpoint 61°F (16°C)
Visibility 9.00 mi
Last update 17 Jun 4:56 am EDT
Extended Forecast for

Stony Brook NY

  • Overnight

    Overnight: A 40 percent chance of showers. Patchy fog. Otherwise, cloudy, with a low around 62. East wind around 6 mph.

    Low: 62 °F

    Chance
    Showers and
    Patchy Fog

  • Tuesday

    Tuesday: A 40 percent chance of showers, mainly before 2pm. Patchy fog before 8am. Otherwise, cloudy, with a high near 72. East wind around 7 mph.

    High: 72 °F

    Chance
    Showers and
    Patchy Fog

  • Tuesday Night

    Tuesday Night: A chance of showers, with thunderstorms also possible after 5am. Patchy fog. Otherwise, cloudy, with a low around 64. Southeast wind 3 to 5 mph. Chance of precipitation is 30%.

    Low: 64 °F

    Chance
    Showers and
    Patchy Fog

  • Wednesday

    Wednesday: A slight chance of showers and thunderstorms before 2pm, then a chance of showers between 2pm and 5pm, then showers likely and possibly a thunderstorm after 5pm. Mostly cloudy, with a high near 81. South wind around 7 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    High: 81 °F

    Slight Chance
    T-storms then
    Showers
    Likely

  • Wednesday Night

    Wednesday Night: Showers likely and possibly a thunderstorm before 8pm, then a slight chance of showers between 8pm and 2am. Mostly cloudy, with a low around 68. South wind around 6 mph. Chance of precipitation is 60%.

    Low: 68 °F

    Showers
    Likely then
    Slight Chance
    Showers

  • Juneteenth

    Juneteenth: A 30 percent chance of showers and thunderstorms after 2pm. Mostly sunny, with a high near 87.

    High: 87 °F

    Mostly Sunny
    then Chance
    T-storms

  • Thursday Night

    Thursday Night: A chance of showers and thunderstorms before 8pm, then a chance of showers between 8pm and 11pm. Partly cloudy, with a low around 68. Chance of precipitation is 30%.

    Low: 68 °F

    Chance
    T-storms then
    Partly Cloudy

  • Friday

    Friday: Sunny, with a high near 85.

    High: 85 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 67.

    Low: 67 °F

    Mostly Clear

Detailed Forecast

Overnight
A 40 percent chance of showers. Patchy fog. Otherwise, cloudy, with a low around 62. East wind around 6 mph.
Tuesday
A 40 percent chance of showers, mainly before 2pm. Patchy fog before 8am. Otherwise, cloudy, with a high near 72. East wind around 7 mph.
Tuesday Night
A chance of showers, with thunderstorms also possible after 5am. Patchy fog. Otherwise, cloudy, with a low around 64. Southeast wind 3 to 5 mph. Chance of precipitation is 30%.
Wednesday
A slight chance of showers and thunderstorms before 2pm, then a chance of showers between 2pm and 5pm, then showers likely and possibly a thunderstorm after 5pm. Mostly cloudy, with a high near 81. South wind around 7 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Wednesday Night
Showers likely and possibly a thunderstorm before 8pm, then a slight chance of showers between 8pm and 2am. Mostly cloudy, with a low around 68. South wind around 6 mph. Chance of precipitation is 60%.
Juneteenth
A 30 percent chance of showers and thunderstorms after 2pm. Mostly sunny, with a high near 87.
Thursday Night
A chance of showers and thunderstorms before 8pm, then a chance of showers between 8pm and 11pm. Partly cloudy, with a low around 68. Chance of precipitation is 30%.
Friday
Sunny, with a high near 85.
Friday Night
Mostly clear, with a low around 67.
Saturday
Mostly sunny, with a high near 85.
Saturday Night
Mostly cloudy, with a low around 68.
Sunday
Mostly sunny, with a high near 88.
Sunday Night
Partly cloudy, with a low around 71.
Monday
Mostly sunny, with a high near 90.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Stony Brook NY
 40.92°N 73.15°W (Elev. 36 ft)
Last Update:
3:36 am EDT Jun 17, 2025
Forecast Valid:
5am EDT Jun 17, 2025-6pm EDT Jun 23, 2025
 
Forecast Discussion
 
Get as KML Get as XML

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