In Connecticut, one person was found dead after being swept away by floodwaters near Little River in Oxford and another was still missing Monday.
Oxford Fire Chief Scott Pellitier said one person was in a car and the other was clinging to a sign when a rapid stream of water swept them away.
Firefighters rescued more than a dozen people from a flooded restaurant in Beacon Falls, Connecticut, about 5 miles east of Oxford, on Sunday.
Floodwaters trapped 18 people inside the Brookside Inn Restaurant, and there were concerns that the restaurant's structure might be compromised.
Firefighters used an aerial ladder to get the people out of the restaurant and rescue a resident in a nearby apartment.
"The water is literally enveloping this whole restaurant. There was nowhere for them to go," said Jeremy Rodrigo, a volunteer firefighter in Beacon Falls. "And we were worried about the structural integrity of the restaurant because there are literally cars floating by and large objects that were hitting the building."
In Southbury, police asked residents via Facebook to stay home while roads were closed and crews responded to emergencies.
In nearby Danbury, city officials said in a statement that a mudslide prompted the evacuation of a home.
Fairfield County had 10 inches of rainfall on Sunday. Numerous roads were closed to traffic.
The Danbury Fire Rescue boat was ready to help
Ana Sousa is now homeless after being evacuated from her apartment complex on Plumtrees Road in Danbury. Thankfully her family lives nearby.
"There's explosion of gas that she said. And then she got evacuated, and then she went to my house. Everything broke and she went to my house, said her granddaughter, Claire De Souza
Two people missing after being swept away by floodwaters
On Long Island, Suffolk County declared a state of emergency after large amounts of rainfall overnight pummeled the north shore, washing away roads and prompting rescues and evacuations.
Significant damage was reported from the heavy rain and flooding.
Suffolk County Police said they received dozens of calls from drivers stuck in floodwaters and from residents whose basements and first floors were flooded.
Multiple water rescues in Nesconset, Ronkonkoma, Smithtown and St. James.
Crews were out early Monday morning working to pump water from the intersection of El Dorado Drive and Jericho Turnpike in East Northport ahead of the morning rush hour.
Suffolk County Executive Ed Romaine will hold a news conference Monday morning at the site of a road collapse in Stony Brook.
Flooding on roadways strands drivers in parts of Suffolk County
The rain in New Jersey was powerful enough to bring traffic to a grinding halt. Hundreds of vehicles had nowhere to go on the Garden State Parkway in East Orange.
The New Jersey Turnpike Authority issued a travel alert for weather-related closures on the Garden State Parkway and New Jersey Turnpike.
The water there practically swallowed half a dozen cars, including a state trooper's cruiser. Without anywhere to go, some drivers got out of their cars.
Tim Clancy had been on a date at the Woodland Park Barnes and Noble when a flash flood enveloped the shopping center's parking lot. Clancy and his date tried to plow through the water, got stuck, and wound up at a Popeyes - soaked, and waiting for a ride.
"You point and laugh, you know, it's like 'that poor sucker' - now we're the sucker tonight for sure," Clancy said.
Clancy said he didn't expect his date to end at Popeye's.
"We're vegan. We don't even eat chicken," he added.
According to meteorologist Lee Goldberg, the flooding was caused by a slow-moving upper trough and associated surface front.
Low pressure developed nearby and slowly drifted across the area, enhancing the rainfall.
With abundant moisture in place, rainfall rates up to 3-4 inches per hour led to extreme flash flooding.
While this wasn't moisture from Ernesto, Lee explained, "the hurricane certainly jammed up the playing field, slowing down the east coast trough and associated surface front."
Get the latest weather alerts here.
All Amtrak service between New York and Philadelphia was restored late Sunday night after heavy flooding in Newark.
Newark Light Rail service was suspended in both directions between Grove Street and Park Avenue, but resumed later.
On the Long Island Railroad, service on the Port Washington Branch was partially suspended between Great Neck and Port Washington as a result of signal issues.
NICE bus service was cross-honoring LIRR tickets between the two stations.
Metro North reported a service suspension on the Danbury and Waterbury branch due to flooding. Alternatively, commuters can take the Harlem or New Haven lines.
The Associated Press contributed to this report.
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