By late afternoon Tuesday, the day's rain had moved out of the area, with just a 30 percent chance of more precipitation in the early evening as a cold front moves in, said Mike Layer, meteorologist with the National Weather Service based in Upton.
Low temperatures Tuesday night are expected to be in the mid- to low 60s, the weather service said.
The heaviest rainfall had been just to the south and west, with most areas of Long Island getting less than an inch, he said.
In a tweet shortly before 11:30 a.m., the weather service said: "Back edge of the heaviest rain now approaching NYC. Heaviest rain still south of Long Island and east of NJ. Lots of lightning south of LI."
That meant that "a solid batch of rain" -- though not the possible 1 to 2 inches an hour that had been forecast -- was stretching across Long Island, rain that "will be ending from west to east," said Tim Morrin, weather service meteorologist based in Upton.
Apart from a possible "brief sprinkle or drizzle" during daylight hours, Nassau was expected to see the end of the rain by about 2 p.m. and the Twin Forks by about 4 p.m., he said.
A cold front is forecast to arrive in the early evening hours, and that could be preceded by "a narrow line of showers," he said.
Earlier, a flood advisory was issued for Nassau County that expired at 11:30 a.m., as radar showed heavy showers and thunderstorms moving east into northeast New Jersey, the weather service said.
A flash-flood watch for Nassau and Suffolk counties was lifted shortly after noon, along with a hazardous weather outlook that spoke of possible strong winds and even a brief, isolated tornado.
The precipitation is a result of low pressure moving northeast from the mid-Atlantic region and an associated warm front, the service said.
By about 1:30 p.m. area airports were reporting no significant flight delays, according to the Federal Aviation Administration website.
The pilot of JetBlue Flight 2, an Airbus A320, earlier reported that the aircraft was struck by lightning as it was inbound to Kennedy, according to an FAA spokeswoman. The aircraft landed safely just before 11 a.m., after having originated from Fort Lauderdale-Hollywood International Airport, she said. The FAA is investigating.
After Tuesday, clearer weather is forecast into the weekend, with sunny skies and temperatures in the high 70s, the service said.
With Patricia Kitchen
and John Valenti