Evacuations on the east coast have begun, as the areas prepare to be slammed by Hurricane Earl.

The storm reverted to a category 3 but is still keeping winds of 135mph.

President Barack Obama said that officials need to be prepared for a “worst case” scenario in a call to the Federal Emergency Management Agency (FEMA).

An island on North Carolina's Outer Banks is being evacuated and visitors are being asked to leave another one.

The narrow islands are connected by a single main road and officials worry that waves washing over it will cause danger to travelers.

FEMA has issued a warning, telling people along the eastern seaboard to be vigilant and to follow official bulletins.

Meteorologists at the National Hurrican Center say they expect the hurricane to turn north and churn parallel along the east coast.

"The most important thing for people living in Earl's potential tract to do is to listen to and follow the instructions of their local officials," FEMA administrator Craig Fugate said.

A hurricane warning has been given to the east coast of the US from Bogue Inlet, NC nort-eastward to the NC/Virginia border, including the Pamlico and Albermarle sounds.

The hurricane watch was adjusted northward and now extends from the NC/VA border northward to Cape Henlopen, Delaware.

A warning means that hurricane conditions are expected somewhere in the affected area, with the first tropical storm-force winds within 36 hours. A watch is the same, but within 48 hours.

The local authorities in the Outer Banks expect the storm to hit 80 miles off from the islands, which are a tourist destination, meaning high winds and waves are expected.

Hatteras Island is being evacuated of tourists, while both residents and visitors have been told to leave Ocracoke Island to the South.

The hurricane is currently east of the central Bahamas and is moving north-west.

"Large swells from Earl should affect the Bahamas and the south-eastern coast of the United States today [Wednesday]. These swells will likely cause dangerous surf conditions and rip currents," the NHC said.

The Labor Day weekend marks the end of a holiday season and many Americans use it to head for the beach.

On Monday, the hurricane slammed into north-eastern Caribbean islands and Puerto Rico, causing flooding and power outages.

Earl is being tailed closely by Topical Storm Fiona, currently east of the Leeward Isles with winds of up to 40mph.