Tropical storm-force winds extend outward up to 195 miles, the hurricane center said.
"The deepest water will occur along the immediate coast in areas of onshore winds, where the surge will be accompanied by large and destructive waves, " it said.
An onlooker checks out the heavy surf at the Avalon Fishing Pier in Kill Devil Hills.
The wind howled and sheets of rain splattered against windows of a hotel before daybreak in Wilmington, where Sandie Orsa of Wilmington sat in a lobby lit by emergency lights after the power failed.
The No. 1 priority, he said, is to save lives.
In Carolina Beach, North Carolina, authorities have stopped allowing traffic to the island via the only bridge between the island and the mainland.
As of 5 a.m., Florence was 25 miles (55 kilometers) east of Wilmington, North Carolina.
Farther up the coast, in New Bern, about 150 people waited to be rescued from floods on the Neuse River, WXII-TV reported. Emergency crews are attempting to respond to more than a hundred calls for rescues.
Hurricane Florence's leading edge is battering the Carolina coast, bending trees and shooting frothy sea water over streets, as the hulking storm closes in with 160kph winds for a drenching siege that could last all weekend.
This satellite image provided by NOAA shows Hurricane Florence off the eastern coast of the United States on Thursday.
WNBA Champions Storm vs Mystics Game 3 Recap
No one mentioned it publicly during the five-month run up to the WNBA Finals because they knew Sue Bird wouldn't approve. The 98-82 win adds to Seattle's 89-76 and 75-73 victories that they secured in games one and two, respectively.
"This threat will continue into next week", said Jeff Stern, Virginia's state coordinator of emergency management, during a Thursday evening news conference.
"There were a couple of points when I was kind of questioning my decisions in life", he said on Friday after a harrowing night of whipping winds and soaking rain as Florence bullied across the North Carolina coast. Another 400 people were in shelters in Virginia, where forecasts were less dire.
North Carolina corrections officials said more than 3,000 people were relocated from adult prisons and juvenile centres in the path of Florence, and more than 300 county prisoners were transferred to state facilities.
The National Hurricane Center said early Friday that a gauge in Emerald Isle, North Carolina, recently reported 6.3 feet (1.92 meters) of inundation. The homes of about 10 million were under watches or warnings for the hurricane or tropical storm conditions.
Around midday, Spanish moss blew sideways in the trees as the winds increased in Wilmington, and floating docks bounced atop swells at Morehead City.
Coastal towns in the Carolinas were largely empty, and schools and businesses closed as far south as Georgia.
Florence was seen as a major test for FEMA, which was heavily criticized as slow and unprepared a year ago for Hurricane Maria in Puerto Rico, where the storm was blamed for almost 3,000 deaths in the desperate months that followed.
Florence's top sustained wind speeds dropped from a high of 140 miles per hour (225 kph) to 110 miles per hour (175 kph) as its outer rain bands approached the North Carolina coast early Thursday, reducing the storm from Category 4 to Category 2, but forecasters warned that the enormous wind field has been growing larger, raising the risk of the ocean surging on to land.
The impact of Florence will be widespread, with destructive winds, life-threatening storm surge, unsafe surf, torrential rainfall, flooding and the potential for tornadoes. Meteorologists at the National Weather Service's Wilmington office are waiting for the National Hurricane Center to confirm the track of the eyeball, which typically has the storm's strongest winds.
Florence was seen as a major test for the Federal Emergency Management Agency, which was heavily criticised as slow and unprepared previous year for Hurricane Maria in Puerto Rico.
Others were at home hoping for the best.
"Fortunately, we haven't found anything that's come down on the house", he said.