Hurricane Earl grew to a Category 4 storm Monday as it lashed the northeastern Caribbean with ferocious winds and heavy rain.

As it roared past the British Virgin Islands, it had maximum sustained winds of 215 kilometres per hour.

Earl is expected to pass Cape Hatteras, North Carolina on Thursday night or Friday morning, then to move off the U.S. northeast coast and drive towards the Canadian Maritimes, making landfall by Friday night or Saturday morning.

"A ridge of high pressure south of the lower Great Lakes should give it a bit of a kick eastward, then it seems to be a straight line for the south shore of Nova Scotia," said CTV meteorologist Cindy Day.

Some forecasters expect the system to build in intensity to the midpoint in the week, then slow down as the week goes on.

By the time it hits the Maritimes, Earl is likely to drop to Category 1 or Category 2 status.

"As it moves into the colder waters and encounters more vertical wind sheer, were expecting it to decrease in intensity," Jessica Shauer of the U.S. National Hurricane Center told CTV News Channel.

However, she cautioned that forecasting storm activity that is four or five days away is an imperfect science, and the situation could change quickly and dramatically.

2003's Hurricane Juan was a Category 2 and left a swath of damage from Nova Scotia to Prince Edward Island.

The hurricane centre says it's too early to say what impact the storm will have on the U.S. and Canada.

Forecasters say Earl will brush along the U.S. east coast, closest to North Carolina, with pounding surf along much of the eastern seaboard.

"Folks from the Carolinas northward through the Mid-Atlantic and New England need to be paying attention to Earl and the forecasts as they get updated through the week," Brennan said.

On Monday Earl brought heavy rain and flooding to the northern Leeward Islands but did not cause any major damage.

Warnings have been put into effect for the following locations:

• Puerto Rico, including the islands of Culebra and Vieques
• U.S. Virgin Islands
• British Virgin Islands
• Turks and Caicos Islands

The U.S. National Hurricane Center also listed a tropical storm watch for the southeastern Bahamas.

Earl could bring waves and storm surges of about 1.2 metres above normal for some islands.

Meanwhile, Hurricane Danielle weakened to a post-tropical storm as it headed over the open Atlantic northeast of Bermuda.

With files from The Associated Press