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

65°F

18°C

Humidity 90%
Wind Speed Calm
Barometer 30.13 in (1020.1 mb)
Dewpoint 62°F (17°C)
Visibility 10.00 mi
Last update 5 Aug 2:56 am EDT
Extended Forecast for

Lake Ronkonkoma NY

  • Overnight

    Overnight: Partly cloudy, with a low around 63. Calm wind.

    Low: 63 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 83. Calm wind becoming south 5 to 7 mph in the afternoon.

    High: 83 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: A 30 percent chance of showers after 2am. Mostly cloudy, with a low around 72. South wind around 5 mph.

    Low: 72 °F

    Mostly Cloudy
    then Chance
    Showers

  • Thursday

    Thursday: Mostly sunny, with a high near 87. Heat index values as high as 99. Southwest wind 5 to 11 mph.

    High: 87 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: A 30 percent chance of showers and thunderstorms before midnight. Partly cloudy, with a low around 74. South wind 5 to 9 mph becoming light southwest after midnight.

    Low: 74 °F

    Chance
    Showers then
    Partly Cloudy

  • Friday

    Friday: A 40 percent chance of showers after 2pm. Mostly sunny, with a high near 89.

    High: 89 °F

    Sunny then
    Chance
    Showers

  • Friday Night

    Friday Night: A 40 percent chance of showers before midnight. Mostly cloudy, with a low around 73.

    Low: 73 °F

    Chance
    Showers then
    Mostly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 88.

    High: 88 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 73.

    Low: 73 °F

    Partly Cloudy

Detailed Forecast

Overnight
Partly cloudy, with a low around 63. Calm wind.
Wednesday
Mostly sunny, with a high near 83. Calm wind becoming south 5 to 7 mph in the afternoon.
Wednesday Night
A 30 percent chance of showers after 2am. Mostly cloudy, with a low around 72. South wind around 5 mph.
Thursday
Mostly sunny, with a high near 87. Heat index values as high as 99. Southwest wind 5 to 11 mph.
Thursday Night
A 30 percent chance of showers and thunderstorms before midnight. Partly cloudy, with a low around 74. South wind 5 to 9 mph becoming light southwest after midnight.
Friday
A 40 percent chance of showers after 2pm. Mostly sunny, with a high near 89.
Friday Night
A 40 percent chance of showers before midnight. Mostly cloudy, with a low around 73.
Saturday
Mostly sunny, with a high near 88.
Saturday Night
Partly cloudy, with a low around 73.
Sunday
Sunny, with a high near 89.
Sunday Night
Mostly clear, with a low around 72.
Monday
Mostly sunny, with a high near 89.
Monday Night
A 30 percent chance of showers. Partly cloudy, with a low around 72.
Tuesday
A 40 percent chance of showers. Mostly sunny, with a high near 88.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Lake Ronkonkoma NY
 40.83°N 73.11°W (Elev. 98 ft)
Last Update:
2:22 am EDT Aug 5, 2026
Forecast Valid:
3am EDT Aug 5, 2026-6pm EDT Aug 11, 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