Hurricane Earl has battered North Carolina's coast with rain, winds and waves and is swirling up the US east coast towards New England and Canada as a weakened but still dangerous storm.

The impact of the Category 2 storm appears to be less than originally expected as Earl churns north parallel to the US Atlantic coast hours after it was downgraded from a Category 4 hurricane.

Local emergency officials said no casualties or major structural damage had been reported so far. At least one coastal road was cut off by waves washing over it.

"Certainly conditions are not as severe as they could have been," said Sandy Sanderson, the director of emergency services in Dare County.

Earl was gusting at a sustained top windspeed of 105 miles per hour and its centre passed east of the Outer Banks islands that jut into the Atlantic, the US National Hurricane Center said.

A slight further weakening is forecast during the next 24 to 36 hours but Earl is expected to remain as a large hurricane as it turns towards the northeast and heads for southeastern New England.