Forecasters say the hurricane's strength is expected to fluctuate but it still will be a unsafe storm by the time it reaches the coast of SC or North Carolina on Thursday.
North Carolina Gov. Roy Cooper said his state is "in the bull's-eye" and urged people to "get ready now". She grew up on the shore, and says this will be only the second time she's evacuated.
Hurricane watches have been issued for the majority of the South and North Carolina coasts.
The airlines affected by the waivers vary from city to city, but most are now in the path of Florence as meteorologists are tracking the category 4 storm. Ilija Cesal told the newspaper he wouldn't worry about buying extra water or other supplies for a few more days.
"We do not want to risk one SC life in this hurricane", Governor Henry McMaster told a news conference.
At 11 p.m. EDT, the storm's center was located about 465 miles (750 kilometers) south-southeast of Bermuda and about 1,085 miles (1745 kilometers) east-southeast of Cape Fear, North Carolina.
The hurricane center warned that the swells are likely to cause "life-threatening" surf and current conditions.
Helene is about 195 miles (320 km) west-southwest of the southernmost Cabo Verde Islands, packing maximum sustained winds of 85 miles per hour (140 km per hour), the NHC said, adding slow weakening should begin by late Tuesday. She said it was built in 2009 in Buxton, North Carolina, up on a ridge, and made to withstand a hurricane.
"This one really scares me", National Hurricane Center Director Ken Graham said.
As of Monday evening, Hurricane Florence was moving west-northwest at 13 miles per hour. Its maximum sustained winds are at 105 miles per hour (165 kph). It comes after he approved a similar declaration for North and SC, which are now in the bull's-eye of the powerful Category 4 storm.
"This is going to be big", said Victoria Oliva, a meteorologist with the National Weather Service in Wilmington said early Monday morning. While Helene is forecast to slide out to sea away from land, Isaac is a very real threat in the Caribbean later this week, the hurricane center said.
Tropical storm winds are forecast to hit the region sometime Thursday morning, with landfall occurring late Thursday night.
"There is an increasing risk of two life-threatening impacts from Florence: storm surge at the coast, freshwater flooding from a prolonged and exceptionally heavy rainfall event inland, and damaging hurricane-force winds", the NHC warned.