Revived Hurricane Ian slams coastal South Carolina, ripping apart piers and filling neighbourhoods with calf-high water in the US state, after causing catastrophic damage in Florida.

Human-caused climate change increased the extreme rain that Ian unleashed by over 10 percent, US scientists say.
Human-caused climate change increased the extreme rain that Ian unleashed by over 10 percent, US scientists say. (AP)

Hurricane Ian, one of the worst storms ever to hit the United States, has roared into South Carolina, delivering a powerful second punch after walloping Florida.

The National Hurricane Center (NHC) said on Friday Ian made landfall near Georgetown, South Carolina, as a Category 1 hurricane with maximum sustained winds of 140 kilometres per hour.

It was later downgraded to a post-tropical cyclone but the NHC warned coastal residents that the "dangerous storm surge, flash flooding and high wind threat continues."

As for storm-ravaged Florida, President Joe Biden said: "We're just beginning to see the scale of the destruction."

"It's likely to rank among the worst in the nation's history," he said of Ian, which barrelled into Florida's southwest coast on Wednesday as a Category 4 storm, a tick shy of the most powerful on the Saffir-Simpson wind scale.

More than 350,000 people were without power in North and South Carolina, according to the tracking website poweroutage.us.

READ MORE: Ian regains hurricane strength as it nears South Carolina

'American crisis'

Florida state officials said 23 people have died so far.

Seventeen migrants also remain missing from a boat that sank during the hurricane on Wednesday, according to the Coast Guard.

One person was found dead and nine others rescued, including four Cubans who swam to shore in the Florida Keys.

With damage estimates running into the tens of billions of dollars, Biden said it's "going to take months, years to rebuild."

"It's not just a crisis for Florida," he said. "This is an American crisis."

CoreLogic, a firm that specialises in property analysis, said wind-related losses for residential and commercial properties in Florida could cost insurers up to $32 billion while flooding losses could go as high as $15 billion.

"This is the costliest Florida storm since Hurricane Andrew made landfall in 1992," CoreLogic's Tom Larsen said.

READ MORE: Hurricane Ian slams Florida as Category 4 fury

Florida, Cuba's devastation

In Florida, rescue teams were assisting survivors on Friday and the Coast Guard said it had made 117 rescues using boats and helicopters of people trapped in flooded homes.

Governor Ron DeSantis said hundreds of other rescue personnel were going door-to-door "up and down the coastline."

DeSantis said the coastal town of Fort Myers where the hurricane made landfall, was "ground zero" but "this was such a big storm that there are effects far inland."

Many Floridians evacuated ahead of the storm, but thousands chose to shelter in place and ride it out.

More than 1.6 million Florida residents were still without electricity on Friday and two barrier islands near Fort Myers -- Pine Island and Sanibel Island -- were cut off after the storm damaged causeways.

Before pummeling Florida, Ian plunged all of Cuba into darkness after downing the island's power network.

Electricity was gradually returning, but many homes remain without power.

The human-induced climate crisis is resulting in more severe weather events across the globe, scientists say -- including with Ian.

According to rapid and preliminary analysis, human-caused climate change increased the extreme rain that Ian unleashed by over 10 percent, US scientists said.

READ MORE: Strengthening Hurricane Ian lashes Cuba en route to Florida

Source: AFP