The outer reaches of Hurricane Florence have begun lashing coastal North Carolina with heavy winds and flooding, ahead of an expected landfall that is tipped to bring walls of water and lingering downpours.

The centre of Florence is due to hit North Carolina’s southern coast later Friday, then drift southwest before moving inland on Saturday.

That will give the category 2 hurricane enough time to drop as much as one metre of rain in places, according to the National Hurricane Centre.

An estimated 10 million people live in the storm’s path, and coastal businesses and homes were boarded up in anticipation on Thursday.

More than one million people have been ordered to evacuate the coasts of the Carolinas and Virginia and thousands have moved to emergency shelters, officials said.

More then a million people have been ordered to evacuate the coast. Photo: Getty

Florence’s maximum sustained winds were clocked on Thursday at 165km/h after it was downgraded to a category 2 on the five-step Saffir-Simpson scale.

Some people who had rejected calls to evacuate the targeted area took walks along the water as they tried to enjoy a few final hours of normalcy before Florence’s fury arrived.

North Carolina Governor Roy Cooper warned against complacency.

“Hurricane Florence was uninvited but she’s just about here anyway,” he said at a news conference.

“Stay on guard. This is a powerful storm that can kill. Today the threat becomes a reality.”

The storm’s centre was about 180km east of Wilmington, North Carolina, at 2pm local time on Thursday but tropical storm-strength winds and heavy rains were already hitting North Carolina’s Outer Banks barrier islands.

The main highway in the Outer Banks was closed in parts as seawater pushed in. Flooding from rain and rising rivers was also reported in New Bern.

Some 11,000 power outages have been reported in North Carolina.

The National Hurricane Centre said the threat of tornadoes was increasing as the storm neared shore.

Florence could bring wind-driven storm surges of seawater as high as 4 metres, which could push in as far as 3km. Heavy rains were forecast to extend into the Appalachian mountains, affecting parts of Alabama, Tennessee, Kentucky and West Virginia.

Tye rain and heavy winds are expected to last for days: Photo: NASA

Emergency declarations were in force in Georgia, South and North Carolina, Virginia, Maryland and the District of Columbia.

Millions of people are expected to lose power and it could take weeks to resolve the outages.

Near the beach in Wilmington, a Waffle House restaurant, part of a chain with a reputation for staying open during disasters, had no plans to close, even if power is lost. It had long lines on Thursday.

-Reuters