Claudette regained tropical storm strength over the Carolinas early Monday after leaving a trail of devastation across the South — including a 15-car wreck that killed nine children.

The storm had sustained winds of 40 mph Monday as it made its way toward the Atlantic Ocean and north toward Nova Scotia, where it will touch down Tuesday, the National Hurricane Center said.

A tropical storm warning was in effect Monday along the North Carolina coast, the National Weather Service said — after having downgraded the storm to a “depression” on Saturday. Parts of Florida, Georgia and South Carolina, meanwhile, continued to see heavy rains and “isolated” flooding, officials said.

“An isolated tornado is possible early this morning over parts of the Outer Banks,” said Brad Reinhart, a specialist with the National Hurricane Center.

“By afternoon, we expect the system to be well offshore,” Reinhart said.

Towns across Alabama, Mississippi and Louisiana reported 10 inches or more rainfall over the weekend, with peak wind gusts over 60 mph, the NWS said.

Saturday’s 15-car pile-up occurred amid massive flooding across Alabama. The victims included eight girls traveling from the beach on a bus operated by a ranch for “troubled” teens, along with 29-year-old Tennessee firefighter Cody Fox and his 9-month-old daughter.

Investigators from the National Transportation Safety Board will probe the crash, the agency said Sunday.

An Alabama man in his early 20s and his 3-year-old son also died in the storm Saturday when a tree collapsed on their mobile home outside Tuscaloosa, Alabama, local officials said.

With Post wires