This satellite image taken Tuesday afternoon at 1:45 PM ET shows Hurricane Bill with a more distinct eye as it swirls to the east of the Lesser Antilles. (Weather Underground/Associated Press)

The first hurricane of the Atlantic season became a major storm on Tuesday as it continued to gain strength.

The U.S. National Hurricane Center upgraded Hurricane Bill to a Category 3 storm after reconnaissance aircraft found the storm had sustained winds whipping up to 205 km/h, with higher gusts.

The storm was located about 895 kilometres east of the Leeward Islands at 11 p.m. AT, and was moving west-northwest at about 24 km/h.

The hurricane centre said in a statement that Bill is expected to make a gradual turn to the northwest on Wednesday, and the core of the storm is predicted to pass well to the northeast of the northern Leeward Islands late Wednesday and early Thursday.

Bill could possibly gain more strength, and Todd Kimberlain, a forecaster at the centre, said the most significant threat is to the island of Bermuda. The storm could pass by there in three or four days, although forecasts suggest it may also miss land entirely and pass between Bermuda and the eastern U.S. coast.

"We are keeping an eye on it for sure," said Nick Camizzi, a forecaster with Bermuda's weather service.

Hurricanes are categorized on the Saffir-Simpson scale from one to five, indicating the storm's intensity at a given time.

Heading north

CBC meteorologist Peter Coade said the storm is tracking north, but it's expected to weaken and curve away from Nova Scotia.

"At this time, I would say the people to benefit from Bill might just be the surfers because we should get a surf along the Atlantic coast by Monday and Tuesday as it passes by," Coade said.

The two other named storms of the Atlantic hurricane season, Ana and Claudette, have had little effect on any mainland communities.

Tropical storm Ana was weakened to a tropical depression and dissipated before reaching land. But heavy rain from the storm did cause some flooding in Puerto Rico, resulting in some closed roads and schools on Tuesday. There were also some evacuations in the Dominican Republic related to flooding and mudslide risks caused by the rain.

Tropical storm Claudette also quickly weakened after making landfall on Monday along the Florida Panhandle.

With files from The Associated Press