Although it's been downgraded to a category two storm with 105mph winds, officials say there could be feet - rather than inches - of rain.
More than 80,000 people were already without power as the storm began buffeting the coast, and more than 12,000 were in shelters.
A buoy off the North Carolina coast recorded waves almost 30 feet high as Florence churned toward shore.
Weather Underground meteorology director Jeff Masters said Florence eventually could strike as merely a Category 1 hurricane with winds less than 100 miles per hour (160 kph), but that's still enough to cause at least $1 billion in damage.
Storm surges are caused when huge volumes of water are pushed by hurricane-force winds.
"But that's not going to be until Monday", Eliasen said".
"We live in a mobile home so we were just like 'No way, '" she said.
Myrtle Beach, a SC beach resort, was virtually deserted with empty streets, boarded up storefronts and very little traffic.
But North Carolina Gov. Roy Cooper warned: "Don't relax, don't get complacent". "I've got four cats inside the house".
Duke Energy Corp, the biggest utility in the area with over 4 million customers, estimated the storm could cause between 1 million to 3 million outages.
In Myrtle Beach, ABC correspondent Pete Combs painted a starker picture of those who made a decision to stay in place.
About 10 million people could be affected by the storm and more than 1 million had been ordered to evacuate the coasts of the Carolinas and Virginia, jamming westbound roads and highways for miles.
A tornado watch was also in effect for parts of North Carolina.
Brock Long, the administrator of the Federal Emergency Management Agency (FEMA), warned the danger was not only along the coast: "Inland flooding kills a lot of people, unfortunately, and that's what we're about to see", he said.
Several of the images were taken when the ISS was directly over the eye of the hurricane.
Many people in coastal communities have followed the mandatory evacuation orders, but some are vowing to stay put and ride it out.
A state of emergency has been declared in five coastal states - North Carolina, South Carolina, Georgia, Maryland and Virginia.
Despite pleas from state and local officials, some residents rejected calls to evacuate.
"When that last ferry pulls out.it's unnerving to see it pull away and know, 'That's the last chance I have of getting off this island, '" she said Wednesday.