Tropical Storm Arthur gathered strength Wednesday, dampening beach getaways at some of America's most popular coastal areas just days before the July 4 holiday.

Forecasters with the National Hurricane Center said the storm would likely reach hurricane strength over the next couple of days.

"Arthur is expected to become a hurricane by Thursday," the Miami-based NHC said in an advisory.

Residents and tourists along the US East Coast looking forward to long weekends at the beach for US Independence Day were forced to consider changing their plans ahead of the storm.

News reports said that as many as half a million visitors had been expected to pack Carolina beaches for the national holiday, the region's biggest tourist weekend.

Rainfall of up to two inches (five centimeters) was expected in eastern Florida, with about twice as much rain possible in North Carolina, the NHC said.

At 1200 GMT, Tropical Storm Arthur was 100 miles (160 kilometers) northeast of Cape Canaveral, Florida, with maximum sustained winds of 60 miles (95 kilometers) per hour.

Arthur was moving toward the north at six miles per hour, but was expected to pick up speed as it advances toward the popular beaches of North Carolina's Outer Banks.

The storm is the first of the Atlantic hurricane season, which started on June 1 and runs through November 30.