A state of emergency was in effect Thursday in Rockland County, and flooding from the heavy rainstorm remains a problem on several roads.
County Executive C. Scott Vanderhoef described the flooding as the worst in Rockland since tropical storm Floyd in 1999.
Highway flooding stranded several cars, water threatened the generators at Nyack Hospital and several high school graduations were postponed.
Parts of Route 59 were closed, as was Main Street in Nyack. The heavy afternoon downpour also closed sections of the Saw Mill River Parkway and Bronx River Parkway in Westchester County.
Some of the flooding subsided after the rainfall stopped but Clarkstown Supervisor Alexander Gromack said 16 areas were flooded or in danger of flooding.
Heavy rain also flooded roads in Connecticut, where a Flash Flood Warning was issued for Middlesex and New Haven counties.
A tree that fell on a car during the stormy weather killed a man driving on the Merritt Parkway in Stamford.
Turn of River Fire Company Assistant Chief Matt Maounis says two people were taken from the car with injuries and taken to the hospital. One man later died.
Meanwhile, the National Weather Service says a storm blamed for a man's death in Manchester Township, New Jersey was not a tornado.
Police say 69-year-old Henry Burton Jr. of Sayreville died when two trees fell on his car as strong winds, heavy rain and hail roared across the area Wednesday.
About 40 to 60 homes received minor to moderate damage from wind and falling trees.
The weather service says it's still investigating the possibility that another violent storm in Jackson Township on Wednesday might have been a tornado.
On Thursday afternoon, a new round of storms caused street and stream flooding in portions of Bergen County, including Ridgewood and Saddle River. The National Weather Service issued a flash flood warning for both Bergen and Passaic counties and a flood warning for the Saddle River at Lodi.
(The Associated Press contributed to this report)