Florence was about 170 miles east-southeast of Wilmington, N.C., at 8 a.m. ET Thursday, the National Hurricane Center said.
North Carolinians made last-minute preparations and hunkered down to await Florence's arrival.
Florence is moving toward the northwest near 6 miles per hour.
The storm is expected to bring 20-30 inches of rain, which means even areas not prone to flooding could see high water.
National Hurricane Center: Florence about to make landfall in N. Carolina causing life-threatening storm surge.
The city of Jacksonville's statement says people have been moved to the city's public safety center as officials work to find a more permanent shelter.
More than 60 people had to be pulled from a collapsing motel at the height of the storm, and many more who defied evacuation orders were hoping to be rescued.
A National Guardsman directs counterflow traffic traveling west from Myrtle Beach on United States 501 as Hurricane Florence approaches the East Coast, Wednesday, September 12, 2018, in Conway, South Carolina.
That's because the weather systems that usually push and pull a storm are disappearing as Florence nears land around the border between North and SC.
NOAA also has a collection of live feeds, which include Buxton in North Carolina, and Cherry Beach and Folly Beach in SC.
STORM SURGE: The combination of a risky storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline.
"It truly is really about the whole size of this storm", National Hurricane Center Director Ken Graham said.
Benjamin Brown is a reporter for Fox News. He added later, "Most of the fatalities in these tropical systems is water".
"Surviving this storm will be a test of endurance, teamwork, common sense and patience". "That's the second story of a house", North Carolina Gov. Roy Cooper said Thursday morning.
Cooper also requested additional federal disaster assistance in anticipation of what his office called "historic major damage" across the state.
More than 80,000 people were already without power as the storm approached, and more than 12,000 were in shelters.
Prisoners were affected, too.
About 300,000 people have been evacuated from South Carolina, McMaster said.
Officials said some 1.7 million people in the Carolinas and Virginia were warned to evacuate, but it's unclear how many did.
Frustrated after evacuating his beach home for a storm that was later downgraded, retired nurse Frederick Fisher grumbled in the lobby of a Wilmington hotel several miles inland.
Around midday, Spanish moss blew sideways in the trees as the winds increased in Wilmington, and floating docks bounced atop swells at Morehead City. Ocean water flowed between homes and on to streets on the Outer Banks; waves crashed against wooden fishing piers.
Along the North and SC coasts, many have evacuated from their homes, but some are scrambling to finish last-minute preparations as time is running out to evacuate safely.
The storm's intensity held at about 90 miles per hour (144 kph), and it appeared that the north side of the eye was the most risky place to be as Florence moved ashore.
That reduced the winds' destructive power from Category 4 to Category 2, but forecasters warned that the widening storm, and its likelihood of lingering along the coast day after day after day, raises the risk of surging ocean water and torrential rain.
Although the storm is approaching the US coastline as a Category 2 hurricane after weakening from a Category 4 storm, that doesn't mean the storm will be gentle.
"Catastrophic effects will be felt outside the center of the storm due to storm surge as high as 9 to 13 feet".
A similar-strength hurricane, Maria, struck the island of Puerto Rico a year ago, resulting in the deaths of almost 3,000 USA citizens.
Flash flooding, downed trees and power outages will be possible in these regions early next week before Florence finally departs the East Coast on Wednesday or Thursday.