Hurricane Earl, a powerful Category 4 storm, is swirling toward the U.S. East Coast after dumping heavy rain on islands in the northeastern Caribbean.

A house in the outskirts of St. John's, Antigua, is flooded as a river overflows because of heavy rain from Hurricane Earl. (Johnny Jno-Baptiste/Associated Press)Earl was about 235 kilometres east-northeast of the Turks and Caicos at 8 p.m. ET, having moved away from Puerto Rico and the Virgin Islands earlier in the day, the U.S. National Hurricane Center said. Maximum sustained winds were around 215 km/h, the agency said.

Earl might brush the U.S. East Coast late Thursday or Friday before curving back out to sea, potentially swiping New England or Atlantic Canada, forecasters said.

"There's a lot of variability in the track, but basically the scenarios run as far west as Maine to as far east as eastern Newfoundland," said CBC meteorologist Johanna Wagstaffe. "No matter where Earl ends up, we are looking at a rainy, windy and high-waves weekend across the Maritimes and Atlantic Canada."

The National Hurricane Center warned U.S. coastal residents from North Carolina to Maine to watch the storm closely.

In Nova Scotia, people were being urged to prepare for the storm, even though it's not yet clear how the hurricane might affect the province.

Chris Fogerty, program supervisor for the Canadian Hurricane Centre, said the track could take the storm anywhere "from Maine to the eastern tip of Newfoundland, and for Nova Scotia that could lead to vastly different weather scenarios."

Meanwhile, tropical storm Fiona formed just behind Earl and will likely take the same path to affect mostly the northern Leeward Islands.

"So far the forecast is for Fiona to stay tropical storm strength and not become a hurricane," Wagstaffe said.

Hurricane Danielle, which never made landfall, weakened into a tropical storm Monday over the Atlantic.

With files from The Associated Press