By Colleen Jenkins

(Reuters) - Tropical Storm Arthur was expected to reach hurricane strength by Thursday, dousing some July 4 holiday plans on the U.S. East Coast as officials closed beaches and tourist sites and delayed fireworks shows in anticipation of heavy rain and fierce winds.

Hurricane and tropical storm watches were in effect on Wednesday from Florida to North Carolina after the first named storm of the Atlantic hurricane season strengthened overnight, U.S. forecasters said on Wednesday.

Arthur could bring up to 2 inches (5 cm) of rain across the eastern Florida peninsula and coastal North Carolina, and produce dangerous rip currents along the coasts of several Southern states, according to the National Hurricane Center.

The storm remained out at sea with maximum sustained winds of 60 miles per hour (95 km per hour) early on Wednesday, about 100 miles (160 km) east-northeast of Cape Canaveral, Florida, and 275 miles (445 km) south of Charleston, South Carolina.

Moving northward at 6 miles per hour (9 kph), Arthur could be packing hurricane force winds of 85 miles per hour (135 km per hour) when the outer bands brush the Carolinas on Thursday and Friday before weakening, according to the hurricane center's forecast maps.

Officials in Atlantic Beach, North Carolina, said they would move the town's Independence Day fireworks show to Saturday. The National Park Service ordered the evacuation by 5 p.m. Wednesday of visitors from the narrow barrier islands of the Cape Lookout National Seashore on North Carolina’s central coast.

In the more populous Cape Hatteras National Seashore to the north, where up to 10,000 visitors crowd North Carolina’s Hatteras and Ocracoke islands, the park service said it would close campgrounds, lighthouses and beaches beginning at noon (1600 GMT) on Wednesday.


(Additional reporting by Gene Cherry and David Adams; Editing by Susan Heavey)