Hurricane Dorian Lashes U.S. Coast As Bahamas Counts Cost

Hurricane Dorian has raked the southeastern US coast with howling, window-rattling winds and sideways rain, knocking out power to more than 200,000 homes and businesses.

Dorian, re-energised at 185km/h, pushed northward towards North Carolina's dangerously exposed Outer Banks.

Leaving at least 20 people dead in its wake in the devastated Bahamas, Dorian made its way up the eastern seaboard, sweeping past Florida on Wednesday at a relatively safe distance.

From there, the Category 3 storm apparently grazed Georgia, then hugged the South Carolina coast with more serious effects.

An estimated three million people in Florida, Georgia and the Carolinas were warned to evacuate as the storm closed in with the potential for life-threatening storm surge.

Navy ships were ordered to ride it out at sea and military aircraft were moved inland.

At least two deaths were reported on the US mainland, in Florida and North Carolina, both involving men who fell while getting ready for the storm.

The National Hurricane Centre's projected track showed Dorian passing near or over the Outer Banks on Friday, lashing the thin line of islands that stick out from the US coast like a boxer's chin.

Dorian was then expected to peel away from the shoreline.

In an assault that began over Labour Day weekend, Dorian pounded the Bahamas with Category 5 winds up to 300km/h, obliterating entire neighbourhoods and triggering a humanitarian crisis.

Image of Abaco from the air. Photo: Twitter/Travis C-Carroll

It weakened to a Category 2 before strengthening again late on Wednesday. About 830,000 people were under mandatory evacuation orders on the South Carolina coast alone.

More than 1500 people sought refuge in 28 shelters in South Carolina, where rain began falling late on Wednesday in the historic port city of Charleston, situated on a peninsula that is prone to flooding even from ordinary storms.

As Dorian crept dangerously closer to the city, the wind picked up, sending sheets of rain sideways.

Thunder boomed in the night sky, and power flickered on and off.

More than two dozen streets were closed by flooding in the city, where shops and restaurants were boarded up with wood and corrugated metal.

Johnny Crawford navigates his kayak down a flooded street in Charleston. Photo: Meg Kinnard via AAP

Dorian also apparently spun off at least one tornado in North Myrtle Beach, South Carolina, damaging several homes, city spokesman Patrick Dowling said.

No injuries were reported.

Hundreds of shelter animals from coastal South Carolina arrived in Delaware ahead of the storm.

The News Journal of Wilmington, Delaware, said 200 were airlifted early on Tuesday from shelters in danger of flooding.

About 150 more were expected to arrive via land.

Hundreds of thousands of people were also ordered off the Georgia coast.