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.

Fair

61°F

16°C

Humidity 78%
Wind Speed Calm
Barometer 29.88 in (1011.8 mb)
Dewpoint 54°F (12°C)
Visibility 10.00 mi
Last update 15 Apr 2:56 am EDT
Extended Forecast for

Lake Ronkonkoma NY

  • Overnight

    Overnight: Partly cloudy, with a steady temperature around 59. Light southwest wind.

    Low: 59 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 84. Light west wind becoming south 5 to 10 mph in the morning.

    High: 84 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: A chance of showers and thunderstorms before 2am, then a slight chance of showers. Mostly cloudy, with a low around 54. Southwest wind around 6 mph becoming light and variable after midnight. Chance of precipitation is 40%.

    Low: 54 °F

    Chance
    T-storms

  • Thursday

    Thursday: Partly sunny, with a high near 82. Light southwest wind becoming south 5 to 9 mph in the morning.

    High: 82 °F

    Partly Sunny

  • Thursday Night

    Thursday Night: Mostly cloudy, with a low around 55. Southwest wind 3 to 6 mph.

    Low: 55 °F

    Mostly Cloudy

  • Friday

    Friday: A 40 percent chance of showers after 2pm. Partly sunny, with a high near 74.

    High: 74 °F

    Mostly Cloudy
    then Chance
    Showers

  • Friday Night

    Friday Night: A 30 percent chance of showers before 8pm. Mostly cloudy, with a low around 51.

    Low: 51 °F

    Chance
    Showers then
    Mostly Cloudy

  • Saturday

    Saturday: Partly sunny, with a high near 62.

    High: 62 °F

    Partly Sunny

  • Saturday Night

    Saturday Night: Mostly cloudy, with a low around 47.

    Low: 47 °F

    Mostly Cloudy

Detailed Forecast

Overnight
Partly cloudy, with a steady temperature around 59. Light southwest wind.
Wednesday
Mostly sunny, with a high near 84. Light west wind becoming south 5 to 10 mph in the morning.
Wednesday Night
A chance of showers and thunderstorms before 2am, then a slight chance of showers. Mostly cloudy, with a low around 54. Southwest wind around 6 mph becoming light and variable after midnight. Chance of precipitation is 40%.
Thursday
Partly sunny, with a high near 82. Light southwest wind becoming south 5 to 9 mph in the morning.
Thursday Night
Mostly cloudy, with a low around 55. Southwest wind 3 to 6 mph.
Friday
A 40 percent chance of showers after 2pm. Partly sunny, with a high near 74.
Friday Night
A 30 percent chance of showers before 8pm. Mostly cloudy, with a low around 51.
Saturday
Partly sunny, with a high near 62.
Saturday Night
Mostly cloudy, with a low around 47.
Sunday
Showers likely, mainly after 2pm. Mostly cloudy, with a high near 60. Chance of precipitation is 60%.
Sunday Night
Showers likely. Mostly cloudy, with a low around 39. Chance of precipitation is 60%.
Monday
Mostly sunny, with a high near 51.
Monday Night
Mostly clear, with a low around 35.
Tuesday
Sunny, with a high near 54.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Lake Ronkonkoma NY
 40.83°N 73.11°W (Elev. 98 ft)
Last Update:
2:33 am EDT Apr 15, 2026
Forecast Valid:
3am EDT Apr 15, 2026-6pm EDT Apr 21, 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