"Disaster is at the doorstep and is coming in", North Carolina Gov. Roy Cooper said.
Some fluctuations in strength are expected through Thursday morning.
"I'm not approaching Florence from fear or panic", said Brad Corpening, 35, who planned to ride out the storm in his boarded-up delicatessen in Wilmington.
A search-and-rescue team is being deployed by FEMA from Montgomery County in Maryland to help in SC as the area braces for Hurricane Florence.
Florence weakened slightly to a Category 3 storm on a five-step scale but had maximum sustained winds of 125 miles per hour (201 km per hour) as of 2 p.m. EDT (1800 GMT), down from 130 mph earlier in the day.
Meteorologists are warning of potentially catastrophic flooding in the area, with isolated amounts of up to 40 inches of rain expected in parts of SC. Catastrophic flooding and destructive winds are becoming very likely in the eastern Carolinas.
Manure lagoons are about as pleasant as they sound-vast open-air ponds of manure located next to the many hog farms near the North Carolina coast. The only exception was Edisto Beach - that and other areas to the north remain under evacuation orders.
With South Carolina's beach towns more in the bull's-eye because of the shifting forecast, OH vacationers Chris and Nicole Roland put off their departure from North Myrtle Beach to get the maximum amount of time on the sand.
For anyone needing a place to stay to escape the hurricane, both North Carolina and SC are updating their lists of emergency shelters.
Coastal residents are not the only people attempting to move out of harm's way of Hurricane Florence. The port in Charleston, South Carolina, though, was suspending operations from Thursday through Saturday and possibly on Sunday.
Florence is predicted to turn more toward the northwest through Thursday - but then is expected to head more west-northwest and stall a bit over the Carolinas.
She said it will become a "major flooding event".
Deal cited the storm's "forecasted southward track" in a statement declaring a state of emergency.
Experts are saying Florence, a "monster", could be one of the most powerful storms to ever hit the East Coast.
An additional 25 percent of deaths are related to rain, he said.
Authorities, including President Trump and the Federal Emergency Management Agency (FEMA), are urging residents in the Carolinas as well as parts of Virginia and Georgia to evacuate as the storm continues its path.
"Bad things can happen when you're talking about a storm this size", Trump said Wednesday morning.