A severe thunderstorm watch, in effect until 10 p.m., was issued Saturday afternoon for Nassau County, the National Weather Service said.
Earlier Saturday, heavy rain had flooded several stretches of road in Suffolk County, overwhelming a handful of basements and leaving about 2,600 people without power at the height of the storm, officials said.
An urban flood advisory issued for parts of Long Island expired at 10:45 a.m. as the heaviest thunderstorms pushed across the Hamptons on their way out to sea, said David Stark, meteorologist with the weather service in Upton.
Areas affected by the storms included central and eastern Nassau County and most of Suffolk County. Light to moderate rain is still falling in some areas, but the worst downpours were over by 10:30 a.m. for most of Long Island, Stark said.
The stormy weather began about 7 a.m. and gradually worsened, Stark said. By 8 a.m., heavy rain was falling across a large portion of Long Island with most areas seeing about an inch of rainfall per hour. The National Weather Service also received reports of 2 to 3 inches of rain in a few areas, Starks said.
The rains caused water to pool in places with poor drainage, such as underpasses, and some streets and highways, officials said.
In Deer Park, the basements of several homes were flooded, and firefighters had to push three cars trapped by flooding on Long Island Avenue out of the water about 9:30 a.m., said Tony Biolsi, assistant chief of the Deer Park Fire Department. No one was injured, he said.
As of 11:30 a.m., the Sagtikos Parkway was also closed between the Long Island Expressway and Crooked Hill Road because of flooding, the State Police said.
About 1,000 Long Island Power Authority customers remained without electricity as of 3 p.m., according to the outage map on its website.