National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Hazardous Weather Conditions

Current conditions at

Islip, Long Island Mac Arthur Airport (KISP)

Lat: 40.79°NLon: 73.1°WElev: 98ft.

Mostly Cloudy

75°F

24°C

Humidity 60%
Wind Speed SE 9 mph
Barometer 30.13 in (1020.2 mb)
Dewpoint 60°F (16°C)
Visibility 10.00 mi
Last update 12 Sep 12:56 pm EDT
Extended Forecast for

Ronkonkoma NY

Flood Watch September 13, 05:00am until September 13, 02:00pm
Click here for hazard details and duration
Flood Watch

  • This Afternoon

    This Afternoon: Partly sunny, with a high near 77. South wind around 10 mph.

    High: 77 °F

    Partly Sunny

  • Tonight

    Tonight: A chance of showers and thunderstorms between 2am and 5am, then showers and possibly a thunderstorm after 5am. Low around 66. South wind around 8 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    Low: 66 °F

    Mostly Cloudy
    then Showers

  • Sunday

    Sunday: Showers and possibly a thunderstorm before 2pm, then a slight chance of showers. Some of the storms could produce heavy rainfall. High near 78. South wind around 10 mph becoming west in the afternoon. Chance of precipitation is 100%. New rainfall amounts between 1 and 2 inches possible.

    High: 78 °F

    Heavy Rain

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 64. West wind 5 to 8 mph.

    Low: 64 °F

    Partly Cloudy

  • Monday

    Monday: A 20 percent chance of showers before 2pm. Mostly sunny, with a high near 75. North wind 13 to 15 mph.

    High: 75 °F

    Slight Chance
    Showers

  • Monday Night

    Monday Night: Mostly clear, with a low around 56.

    Low: 56 °F

    Mostly Clear

  • Tuesday

    Tuesday: Sunny, with a high near 72.

    High: 72 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 58.

    Low: 58 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 76.

    High: 76 °F

    Mostly Sunny

Detailed Forecast

This Afternoon
Partly sunny, with a high near 77. South wind around 10 mph.
Tonight
A chance of showers and thunderstorms between 2am and 5am, then showers and possibly a thunderstorm after 5am. Low around 66. South wind around 8 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Sunday
Showers and possibly a thunderstorm before 2pm, then a slight chance of showers. Some of the storms could produce heavy rainfall. High near 78. South wind around 10 mph becoming west in the afternoon. Chance of precipitation is 100%. New rainfall amounts between 1 and 2 inches possible.
Sunday Night
Partly cloudy, with a low around 64. West wind 5 to 8 mph.
Monday
A 20 percent chance of showers before 2pm. Mostly sunny, with a high near 75. North wind 13 to 15 mph.
Monday Night
Mostly clear, with a low around 56.
Tuesday
Sunny, with a high near 72.
Tuesday Night
Partly cloudy, with a low around 58.
Wednesday
Mostly sunny, with a high near 76.
Wednesday Night
Mostly clear, with a low around 63.
Thursday
Mostly sunny, with a high near 79.
Thursday Night
Partly cloudy, with a low around 64.
Friday
Mostly sunny, with a high near 78.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Ronkonkoma NY
 40.81°N 73.11°W (Elev. 98 ft)
Last Update:
2:21 am EDT Sep 12, 2026
Forecast Valid:
1pm EDT Sep 12, 2026-6pm EDT Sep 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