CHARLESTON, S.C. — A weakened but still deadly Hurricane Dorian crept up the Southeastern seaboard Wednesday, and millions were ordered to evacuate as forecasters said near-record levels of seawater and rain could swamp the coasts of Georgia and the Carolinas.

The storm, which ravaged the Bahamas with more than a full day of devastating wind and rain, had weakened substantially — dropping from a Category 5 storm to a Category 2. But it still had dangerously high winds and threatened to swamp low-lying regions from Georgia to southeastern Virginia on its trek northward.

“We will experience hurricane-force winds, in at least gusts,” South Carolina Gov. Henry McMaster said at a news conference. Even if the hurricane doesn’t end up hitting the state directly, he said, “there’s still going to be wind and water and if you’re in the coastal area, that water can be treacherous.”

Dorian appeared likely to get dangerously near Charleston, S.C., which is vulnerably located on a peninsula. A flood chart posted by the National Weather Service projected a combined high tide and storm surge around Charleston Harbor of 10.3 feet; the record, 12.5 feet, was set by Hugo in 1989.

Stores and restaurants were boarded up with wood and corrugated metal in Charleston’s historic downtown, and about 830,000 people were under mandatory evacuation orders on the South Carolina coast. More than 1,500 people were in 28 shelters statewide.

Mark Russell, a homeless U.S. Army veteran, said he had been in a shelter since Monday.

“Once the rain comes and the wind hits, it’s going to blow left, right, in and out, and there’s not really a place that you can find” to avoid it, said Russell, 63.

In North Carolina, where authorities said an 85-year-old man died after falling from a ladder while getting ready for the storm, Gov. Roy Cooper warned of the threat of storm surge and flash flooding from heavy rains. The Outer Banks were particularly exposed.

There were boarded up windows and empty parking lots in Wilmington, N.C., ahead of Dorian. But there were plenty of open gas stations and traffic heading both in and out of town.

Nathan May evacuated his Carolina Beach, N.C., home for Hurricane Florence last year. After it didn’t flood and only a few branches were knocked down, he decided he would ride out Dorian.

“I want to see what it is like,” said May, who moved from Arizona a few years ago. “A bunch of the neighbors are having a party and they said we will be OK.”

Georgia’s coastal islands were also at risk, Gov. Brian Kemp said Wednesday.

“We are very worried, especially about the barrier islands getting cut off if we have these storm surges at the same time as ... the high tides,” Kemp said.

The approach of Dorian has left the cobblestone streets of Savannah, Ga.’s downtown historic district largely deserted.

Duke Energy said Dorian could cause more than 700,000 power outages in eastern regions of North Carolina and South Carolina, and Georgia Power said about 2,800 homes and businesses were already without electricity.

The Navy ordered ships at its base in Norfolk, Va., to head to sea for safety, and warplanes at Langley Air Force Base in Hampton, Va., were being moved inland. The commander of the Navy Region Mid-Atlantic issued an emergency evacuation order for military personnel and their dependents in five North Carolina counties.

Weaker but bigger since it slammed the Bahamas with 185 mph winds earlier this week and killed at least 20, Dorian was moving off the Georgia coast at 8 mph late Wednesday afternoon. Forecasters said it had maximum sustained winds of 110 mph and was centered about 130 miles south of Charleston.

A hurricane warning covered about 500 miles of coastline, and authorities warned about 3 million residents to get away before the water and wind rose.

The acting administrator of the Federal Emergency Management Agency, Peter Gaynor, said 4,000 federal responders, 6,000 National Guard members, and 40,000 utility workers were on standby.

In Florida, initially projected to take a direct hit from Dorian, there was relief after the storm passed at a relatively safe distance offshore.