More than 80,000 people were already without power as the storm began buffeting the coast, and more than 12,000 were in shelters.
As of 5 a.m., Florence was 25 miles (55 kilometers) east of Wilmington, North Carolina.
The outer bands of Hurricane Florence drenched the Carolinas on Thursday, flooding roads, gorging rivers and knocking out power in an ominous glimpse of the damage the storm could inflict when it makes landfall on Friday with millions of people in its path.
"There's already water (in the) bottom part of people's houses", Todd Willis, who lives in Kennel Beach, North Carolina, said Thursday night.
Wild horses in the Rachel Carson Reserve in Beaufort, North Carolina will fend for themselves during Hurricane Florence.
That makes sense since the category of a storm is generally determined by its maximum sustained winds; but, researchers have found, the vast majority of deaths (nearly 90%) from hurricanes, tropical storms, or tropical depressions between 1963 and 2012 were attributable to "storm surge, rainfall flooding, high surf, and deaths just offshore".
-Fatal hazards: historically, 49 percent of USA hurricane deaths come from storm surge, 27 percent from rain, 8 percent from wind, 6 percent from surf, 6 percent were offshore and 3 percent from tornadoes.
Ken Graham, director of the hurricane center, said on Facebook the storm surges could push in as far as 3 kilometers (2 miles).
Although Florence has been downgraded from a category four to a category two storm, North Carolina governor Roy Cooper warned: "Don't relax, don't get complacent".
With winds picking up along the coastline early Thursday, federal and state officials had issued final appeals to residents to get out of the path of the "once in a lifetime" weather system.
"But we can't replace us so we made a decision to come here".
Florence is forecast to significantly weaken as it crawls across central South Carolina Saturday.
Hurricane Florence carries a heavy risk of flash floods as it brings up to 13-foot storm surge and a possible 40 inches of rain to the Carolina coast.
Virginia and Georgia are also under states of emergency, but it's North and SC that are positioned to suffer the worst of the storm's wrath.
Not everybody was heeding orders to evacuate, however.
Will Epperson, a 36-year-old golf course assistant superintendent, said he and his wife had planned to ride out the storm at their home in Hampstead, North Carolina, but then reconsidered.
"The shelters are not taking dogs", Ramirez said.
Perched on the porch of his home, carpenter Tony Albright was calmly awaiting Florence's arrival, beer in hand.
"I do worry though about people here because many didn't prepare, you know, because originally they didn't think it was going to be so bad here", Sparks said.
"The only thing missing in there is a hot lady".