Hurricane Earl threatened to bring a violent end to the summer high season on the US Atlantic coast as tourists evacuated beach resorts in North Carolina and storm preparations were underway Thursday along most of the Eastern seaboard.

The eye of the massive category 3 storm was expected to brush North Carolina's picturesque Outer Banks, a vulnerable chain of barrier islands, late Thursday.

At 2 p.m. (1800 GMT), Earl was 395 km south of Cape Hatteras, North Carolina with sustained winds of 205 km per hour.

'Earl is expected to remain a powerful hurricane as it passes near the Outer Banks,' the National Hurricane Centre (NHC) in Miami said.

'Hurricane force winds extend outward up to 150 km from the centre and tropical storm force winds extend outward up to 370 km.'

The hurricane was then projected to move towards southeastern New England Friday night, before gradually weakening. The NHC warned of destructive storm surges, hurricane force winds and heavy rains.

The storm comes ahead of the three-day Labour Day weekend, a popular end-of-summer holiday when many Americans head to the beaches.

Various hurricane warnings and storm watches were posted along the Atlantic coast, from North Carolina, Virginia, Maryland, Delaware and New Jersey to New York, Connecticut, Rhode Island and Massachusetts.

President Barack Obama was 'closely monitoring' the storm's developments, White House spokesman Robert Gibbs said Thursday. Obama Wednesday signed a disaster declaration for North Carolina, giving the Federal Emergency Management Agency (FEMA) authority to begin aiding the state's storm response effort.

'The time of preparing is over, the time of action is now. Don't wait for the next forecast,' said Craig Fugate, FEMA administrator, as he urged residents along the east coast to listen to evacuation orders.