The death toll from Hurricane Helene along the coastline of the state of Florida has risen to at least 64 deaths, while millions remain without power.

"I've never seen so many people homeless as what I have right now," said Janalea England, of Steinhatchee, Florida, a small river town along the state's rural Big Bend, on Saturday as she turned her commercial fish market into a storm donation site for friends and neighbours, many of whom couldn't get insurance on their homes.

Asheville resident Mario Moraga said it's "heartbreaking" to see the damage in the Biltmore Village neighbourhood and neighbours have been going house to house to check on each other and offer support.

"There's no cell service here. There's no electricity," he said.

While there have been deaths in the county, Emergency Services Director Van Taylor Jones said he wasn't ready to report specifics, partially because downed cell towers hindered efforts to contact next of kin.

The storm, now a post-tropical cyclone, was expected to hover over the Tennessee Valley on Saturday and Sunday, the National Hurricane Center said.

It unleashed the worst flooding in a century in North Carolina, where Governor Roy Cooper described it as "catastrophic" as search and rescue teams from 19 states and the federal government came to help.

And in Atlanta, 28.24 centimetres of rain fell over 48 hours, the most the city has seen over two days since record-keeping began in 1878.

President Joe Biden said on Saturday that Helene's devastation has been "overwhelming" and pledged to send help.

Aftermath

About 100 kilometres to the north, cars lined up before sunrise on Saturday at a free food distribution site in Perry, Florida, amid widespread power outages.

"We're making it one day at a time," said Sierra Land, who lost everything in her fridge, as she arrived at the site with her 5- and 10-year-old sons and her grandmother.

Thousands of utility crew workers descended upon Florida in advance of the hurricane, and by Saturday power was restored to more than 1.9 million homes and businesses.

Chris Stallings, director of the Georgia Emergency Management and Homeland Security Agency, said crews were focused on opening routes to hospitals and making sure supplies can be delivered to damaged communities.

Helene was the eighth named storm of the Atlantic hurricane season, which began June 1. The National Oceanic and Atmospheric Administration has predicted an above-average season this year because of record-warm ocean temperatures.