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

53°F

12°C

Humidity 89%
Wind Speed W 14 G 24 mph
Barometer 29.69 in (1005.4 mb)
Dewpoint 50°F (10°C)
Visibility 8.00 mi
Wind Chill49°F (9°C)
Last update 12 Mar 12:56 am EDT
Extended Forecast for

Great River NY

  • Overnight

    Overnight: A chance of showers and thunderstorms. Mostly cloudy, with a low around 48. Southwest wind around 13 mph, with gusts as high as 26 mph. Chance of precipitation is 50%.

    Low: 48 °F

    Chance
    Showers

  • Thursday

    Thursday: Showers, mainly before 5pm. Temperature falling to around 40 by 4pm. Northwest wind 11 to 16 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

    High: 49 °F⇓

    Showers

  • Thursday Night

    Thursday Night: A 30 percent chance of showers before 8pm. Mostly cloudy, then gradually becoming mostly clear, with a low around 30. Northwest wind 7 to 10 mph.

    Low: 30 °F

    Chance
    Showers then
    Mostly Clear

  • Friday

    Friday: Increasing clouds, with a high near 46. Light and variable wind becoming south 10 to 15 mph in the morning.

    High: 46 °F

    Increasing
    Clouds

  • Friday Night

    Friday Night: Mostly cloudy, then gradually becoming mostly clear, with a low around 37. South wind 11 to 15 mph, with gusts as high as 28 mph.

    Low: 37 °F

    Decreasing
    Clouds

  • Saturday

    Saturday: Sunny, with a high near 49.

    High: 49 °F

    Sunny

  • Saturday Night

    Saturday Night: Increasing clouds, with a low around 32.

    Low: 32 °F

    Increasing
    Clouds

  • Sunday

    Sunday: Cloudy, with a high near 47.

    High: 47 °F

    Cloudy

  • Sunday Night

    Sunday Night: Showers, mainly after 2am. Low around 39. Chance of precipitation is 80%.

    Low: 39 °F

    Chance
    Showers then
    Showers

Detailed Forecast

Overnight
A chance of showers and thunderstorms. Mostly cloudy, with a low around 48. Southwest wind around 13 mph, with gusts as high as 26 mph. Chance of precipitation is 50%.
Thursday
Showers, mainly before 5pm. Temperature falling to around 40 by 4pm. Northwest wind 11 to 16 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.
Thursday Night
A 30 percent chance of showers before 8pm. Mostly cloudy, then gradually becoming mostly clear, with a low around 30. Northwest wind 7 to 10 mph.
Friday
Increasing clouds, with a high near 46. Light and variable wind becoming south 10 to 15 mph in the morning.
Friday Night
Mostly cloudy, then gradually becoming mostly clear, with a low around 37. South wind 11 to 15 mph, with gusts as high as 28 mph.
Saturday
Sunny, with a high near 49.
Saturday Night
Increasing clouds, with a low around 32.
Sunday
Cloudy, with a high near 47.
Sunday Night
Showers, mainly after 2am. Low around 39. Chance of precipitation is 80%.
Monday
Showers. High near 54. Breezy. Chance of precipitation is 90%.
Monday Night
Showers likely. Mostly cloudy, with a low around 30. Chance of precipitation is 60%.
Tuesday
A 30 percent chance of showers. Partly sunny, with a high near 38.
Tuesday Night
Mostly clear, with a low around 23.
Wednesday
Mostly sunny, with a high near 37.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Great River NY
 40.72°N 73.16°W (Elev. 13 ft)
Last Update:
7:41 pm EDT Mar 11, 2026
Forecast Valid:
1am EDT Mar 12, 2026-6pm EDT Mar 18, 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