A revived Hurricane Ian set its sights on South Carolina's coast and the historic city of Charleston, with forecasters predicting a storm surge and floods after the megastorm caused catastrophic damage in Florida and left people trapped in their homes.

With all of South Carolina’s coast under a hurricane warning, a steady stream of vehicles left Charleston, many likely heeding officials’ warnings to seek higher ground. Storefronts were sandbagged to ward off high water levels in an area prone to inundation.

On Friday morning in Charleston, powerful wind gusts bent tree branches and sent sprays of steadily falling rain sideways. Streets in the 350-year-old city were largely empty, an ordinarily packed morning commute silenced by the advancing storm.

'My stomach was in knots,' says woman who stayed in home during Hurricane Ian. – Reuters

With winds holding at 85 mph (140 kph), the National Hurricane Center's update at 5 a.m. Friday placed Ian about 145 miles (235 km) southeast of Charleston and forecast a “life-threatening storm surge” and hurricane conditions along the Carolina coastal area later Friday.

The hurricane warning stretched from the Savannah River to Cape Fear, with flooding rains likely across the Carolinas and southwestern Virginia, the centre said.

An earlier forecast predicted a storm surge of 5 feet (1.5m) into coastal areas of Georgia and the Carolinas. Rainfall of up to eight inches (20cm) threatened flooding from South Carolina to Virginia.

Hurricane Ian floods downtown Cape Coral, Florida. – Reuters via @trentorr40

In Florida, rescue crews piloted boats and waded through riverine streets Thursday to save thousands of Floridians trapped amid flooded homes and buildings shattered by Hurricane Ian.

Florida Gov. Ron DeSantis said at least 700 rescues, mostly by air, were conducted on Thursday involving the US Coast Guard, the National Guard and urban search-and-rescue teams.

At least six people were confirmed dead in Florida, including two who died Thursday afternoon when their car hydroplaned and overturned in a water-filled ditch in north Florida's Putnam County, while three other people were reported killed in Cuba after the hurricane struck there on Tuesday.

Governor Ron DeSantis says rescue efforts underway in '500-year flood event'. – Reuters

Ian had come ashore on Florida's Gulf Coast as a monstrous Category 4 hurricane, one of the strongest storms ever to hit the US. It flooded homes on both the state's coasts, cut off the only road access to a barrier island, destroyed a historic waterfront pier and knocked out electricity to 2.6 million Florida homes and businesses – nearly a quarter of utility customers. Some 2.1 million of those customers remained in the dark days afterward.

At least four people was confirmed dead in Florida, while three other people were reported killed in Cuba after the hurricane struck there on Tuesday.

In the Fort Myers area, the hurricane ripped homes from their slabs and deposited them among shredded wreckage. Businesses near the beach were completely razed, leaving twisted debris. Broken docks floated at odd angles beside damaged boats. Fires smoldered on lots where houses once stood.

“I don't know how anyone could have survived in there,” William Goodison said.

He spoke amid the wreckage of a mobile home park in Fort Myers Beach where he'd lived for 11 years. Goodison said he was alive only because he rode out the storm at his son's house inland.

The hurricane tore through the park of about 60 homes, leaving many destroyed or mangled beyond repair, including Goodison’s single-wide home. Wading through waist-deep water, Goodison and his son wheeled two trash cans containing what little he could salvage – a portable air conditioner, some tools and a baseball bat.

The road into Fort Myers was littered with broken trees, boat trailers and other debris. Cars were left abandoned in the road, having stalled when the storm surge flooded their engines.

Lee County Sheriff Carmine Marceno said his office was scrambling to respond to thousands of 911 calls in the Fort Myers area, but many roads and bridges were impassable.

Emergency crews sawed through toppled trees to reach stranded people. Many in the hardest-hit areas were unable to call for help because of electrical and cellular outages.

A chunk of the Sanibel Causeway fell into the sea, cutting off access to the barrier island where 6300 people live.

Hours after weakening to a tropical storm while crossing the Florida peninsula, Ian regained hurricane strength over the Atlantic. The National Hurricane Center predicted it would hit South Carolina as a Category 1 hurricane Friday.

Hurricane Ian brings flooding and whipping winds to Fort Myers, Florida. – Reuters 

National Guard troops were being positioned in South Carolina to help with the aftermath, including any water rescues. And in Washington, President Joe Biden approved an emergency declaration for the state, a needed step to speed federal assist for recovery once Ian passes.

The storm was on track to later hit North Carolina, forecasters said. North Carolina Gov. Roy Cooper urged residents to prepare for torrents of rain, high winds and potential power outages.

Visiting the state’s emergency operations centre Thursday, Cooper said that up to seven inches (17.8cm) of rain could fall in some areas, with the potential for mountain landslides and tornadoes statewide.

better than many had feared.

"It was insane," local landscaper Jeffrey Chambers, 53, said, describing sideways rain that erased all visibility.

"I was like 'Please stop already, just stop.' And it kept going and going."

Brenda Siettas, 62, a paraprofessional who works with students, was in the city in 2004 when Hurricane Charley blasted much of her neighborhood away. Buildings constructed since then are more able to withstand hurricane-strength winds, she said.

"They definitely built back much better since Charley," she said.

"Back then I stayed here for two weeks: no power, no water, no sewer."

Joe Dalton, on vacation from Cleveland, Ohio, checks out beached boats at Fort Myers Wharf. – AP

Biden spoke to DeSantis on Thursday, saying his administration was committed to close co-ordination and that Federal Emergency Management Agency Director Deanne Criswell will be in Florida on Friday. Biden said that he would travel to the state when conditions allow.

Biden also approved a disaster declaration, making federal resources available to the counties impacted by the storm.

Damage to roads, buildings and other infrastructure in Florida was seen from above during a flight by Lee County Sheriff's Officers. – Reuters