Hurricane Bill became a dangerous Category 4 storm Wednesday as it churned across the Atlantic and heads for the Canadian Maritimes.

The first hurricane of the Atlantic season, Bill is now packing winds of more than 215 kilometres per hour. Hurricanes of Category 3 or higher on the five-step intensity scale are considered "major" and are the most destructive type.

Today, Bill is expected to pass far northeast of the Leeward Islands, a collection of islands where the Caribbean Sea meets the western Atlantic Ocean that includes Antigua and Saint Kitts.

Bill will then head for Bermuda within the next three days, and could deluge the island nation in heavy winds and rains, says Todd Kimberlain, a forecaster at the U.S. National Hurricane Center. But the hurricane also could move between Bermuda and the eastern coast of the United States without making landfall.

As it continues to travel along the warm waters of the Caribbean, it is expected to stay a strong storm through Friday and Saturday. The hurricane will be bringing large wave swells to Bermuda and portions of the southeastern coast of the United States, the Hurricane Center says.

Bill is expected to move into the region of New England and Canada's Maritimes overnight Sunday or early Monday, heading for the southern area of Nova Scotia.

But by then, Bill will have encountered the cooler waters off North Carolina that will drain it of most of its energy. But the storm could still pack enough winds to be considered a Category 1 hurricane by the time it reaches Nova Scotia and Newfoundland.

Forecasters watching the storm's progress say even if the storm passes far east of Nova Scotia, as it could yet do, it will likely still bring significant rain and wind to the province.

The warm-weather pattern of El Nino over the Pacific Ocean is expected to curb tropical storms in the Caribbean and Atlantic this year, according to the U.S. weather service. The first two months of this year's hurricane season, June and July, passed without any storms being named.

But Paul Duval, a meteorologist with the U.S. National Weather Service, told CTV News Channel earlier this week that just because the season has gotten off to a late start doesn't mean the season won't be a bad one. He noted that even one major hurricane making landfall can create damage that takes years to recover from.