Streets collapsed and flights were delayed as heavy rains lashed the US East Coast as far south as usually sunny Florida, after tornadoes ripped through other parts of the country leaving dozens dead.
A couple stand in the remains of a house two days after a tornado destroyed it, on April 30, 2014 in Louisville, Mississippi
Boston, New York and Washington were all drenched, while in northern Florida authorities rescued people from the roofs of their submerged houses, as forecasters reported up to 22 inches (55 centimeters) of rain soaked some neighborhoods in just a few hours.
Florida Governor Rick Scott instructed the National Guard to deploy 24 high-water vehicles to impacted counties to help with rescue and recovery operations.
"This is a slow moving weather system that will continue east through our state, and families should take precautions to secure essential supplies should they lose power or can't use the roads," he said.
Wet weather delayed scores of flights at several airports, including at Philadelphia International, New York's JFK and Washington's Dulles.
In Baltimore, streets collapsed, washing away cars, The Washington Post reported.
At least 36 people were killed earlier in the week when tornadoes tore through six states west of Florida.
A 67-year-old woman was added to the growing death toll when the vehicle she was driving in became submerged in floodwaters in the Florida city of Pensacola, local media reported.
"It went on and on and on. It was relentless," Cheryl Clendenon, who was stranded in her home in Pensacola Beach until a friend picked her up, told NBC News.
The National Weather Service said the weather woes would continue into Thursday.
"A few thunderstorms may approach severe levels Wednesday night into Thursday along the eastern seaboard with strong winds as the primary threat, although a few tornadoes cannot be ruled out," it said.