Hurricane Matthew's rains triggered severe flooding in North Carolina on Sunday as the deteriorating storm made its exit to the sea, and thousands of people had to be rescued from their homes and cars. The death toll in the U.S. climbed to at least 18, nearly half of them in North Carolina.

The storm was stripped of hurricane status just before daybreak, but the crisis — set off by more than a foot of rain — was far from over.

"As the sun rises in North Carolina and the blue sky returns, our state is facing major destruction and, sadly, loss of life," Gov. Pat McCrory said as the effects of Saturday's deluge became clearer at daylight.

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John Tweedy wades into floodwater surrounding his business as he inspects damage in the wake of Hurricane Matthew on Saturday in McClellanville, South Carolina. (Brian Blanco/Getty Images)

Rivers and creeks overflowed, driving people from their homes and trapping others as much as 160 kilometres inland. The unofficial rainfall totals were staggering: 457 millimetres in Wilmington,  355 millimetres in Fayetteville and 200 millimetres in Raleigh.

McCrory said police and emergency crews had made more than 880 water rescues. In the Fayetteville area alone, emergency workers and police saved nearly 600 people from rapidly rising floodwaters, officials said.

The governor said that five people were missing in the Fayetteville area and that the full scale of the disaster was not yet known because the flooding continued overnight and there were many places that search teams had not yet reached.

Eight people have died in the state, he said. 

"There could be some backroads where we had people swept away. I'm praying that is not going to be," McCrory said.

Greatest danger on the roads

Most of the deaths happened when vehicles were swept away by floodwaters.

Shortly before daybreak, the hurricane was downgraded to a post-tropical cyclone. As of 8 a.m. EDT, the storm was centered about 95 kilometres southeast of Cape Hatteras, N.C., moving out to sea. It still had hurricane-force winds of 120 km/h.

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Floodwaters rise up to homes in an affluent historic neighbourhood after Hurricane Matthew hit Charleston, South Carolina on Saturday. (Jonathan Drake/Reuters)

Forecasters said North Carolina and Virginia could get even more rain and warned of the danger of life-threatening flooding through Monday night.

"Stay home. Most of your church services have been cancelled. There's no reason to go out. Take the day off," Fayetteville Mayor Nat Robertson said.

Matthew also killed more than 500 people in Haiti last week as it plowed through the Caribbean.

Other places south of the Carolinas, meanwhile, began getting back to normal, with millions relieved that the storm wasn't the catastrophe many had been bracing for. In many places, the damage consisted mostly of flooded streets, blown-down signs and awnings, flattened trees and power outages.

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The Florida state road A1A is seen after damage from ocean waters stirred up by the storm in Flagler Beach. (Joe Raedle/Getty Images)

As the skies cleared on Saturday, people started cleaning up, reopening their businesses or hitting the beach. The power started coming back on. And all three major theme parks in Orlando, Fla., including Walt Disney World, were up and running.

Along Daytona Beach's main drag, the Silver Diner had all of its shiny metal siding ripped off the front and sides, leaving only a wood frame exposed. Next door, the window of a souvenir shop had been blown out and the roof and ceiling torn through, leaving pink insulation dangling.

David Beasley, president of Insurance Recovery Inc., surveyed the damage and said that although it looked bad, the main strip was hit harder by Hurricanes Charley and Frances in 2004.

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Damage to the Casablanca Inn is shown in St. Augustine, Florida on Saturday. (Ricardo Ramirez Buxeda/Orlando Sentinel via AP)

"This is not much compared to those two," he said.

On Saturday, Matthew sideswiped two of the South's oldest and most historic cities — Savannah, Ga., and Charleston, S.C. — and also brought torrential rain and stiff wind to places like Myrtle Beach, S.C.

After pounding North Carolina and drenching parts of Virginia, it was expected to veer out to sea, lose steam and loop back around toward the Bahamas and Florida, too feeble to cause any trouble.

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David Reedy braves the wind and rain on the Isle of Palms beach as Hurricane Matthew hits the Isle of Palms, S.C., Saturday, Oct. 8, 2016. (Mic Smith/Associated Press)

For nearly its entire run up the coast from Florida, Matthew hung just far enough offshore that communities did not feel the full force of its winds.

Its storm centre, or eye, finally blew ashore just north of Charleston on Saturday, but only briefly. And by that time, Matthew was just barely a hurricane, with winds of just 120 km/h

Matthew's winds were howling at a terrifying 233 km/h when the hurricane struck Haiti, where five days later the full extent of the tragedy was not yet known because some devastated areas were still unreachable.

About 100 guests and workers had to be evacuated from a Comfort Inn motel in the North Carolina coastal town of Southport after the hurricane cracked a wall and left the roof in danger of collapse, authorities said. And dramatic video showed Fayetteville police rescuing a woman and her small child from their car as rising waters swallowed it.

An estimated 2 million people in the Southeast were ordered to evacuate their homes as Matthew closed in. By hugging the coast, the storm behaved pretty much as forecasters predicted. A shift of just 30 to 50 kilometres could have meant widespread devastation.

"People got incredibly lucky," Colorado State University meteorology professor Phil Klotzbach. "It was a super close call."

While Matthew's wind speed had dropped considerably by the time it hit the Southeast coast, the storm will rank as one of the most powerful hurricanes on record, based on such factors as wind energy and longevity, and as one of the most long-lived major hurricanes, too.

It was a major hurricane — that is, with winds of at least 110 mph — for just over seven days.

Three-quarters of a million people lost power in North Carolina, according to the governor, along with a similar number in South Carolina, 250,000 in Georgia and about 1 million in Florida.

In addition to the eight deaths in North Carolina, there were four in Florida, and three in both Georgia and South Carolina, where a 66-year-old man was found outside his nursing home in Columbia, pinned beneath his electric wheelchair and face-down in standing water from the rains, a coroner said. Some people were killed by falling trees, others by carbon monoxide fumes from a generator.

Property data firm CoreLogic projected that insured losses on home and commercial properties would amount to $4 billion to $6 billion, well below Hurricane Katrina's $40 billion and Superstorm Sandy's $20 billion.​