Independence Day celebrations were upended along the East Coast after Hurricane Arthur struck North Carolina's Outer Banks islands overnight, causing flooding.
Arthur began moving offshore and away from the southern state early Friday and was later downgraded to a Category 1 storm.
The U.S. National Hurricane Center said Arthur's maximum sustained winds have decreased to 90 mph (144 kph) with additional weakening expected. Meanwhile, a new tropical storm warning was issued for Nova Scotia in Canada, where Arthur is expected to head as it moves northeast.
Overnight, Arthur had strengthened to a Category 2 storm with winds of 100 mph (160 kph) Thursday evening before passing over North Carolina's Outer Banks — a 200-mile (320-kilometre) string of narrow barrier islands with about 57,000 permanent residents. The islands are susceptible to high winds, rough seas and road-clogging sands, prompting an exodus that began Wednesday night.
The first named storm of the Atlantic hurricane season was moving northeast Friday morning after turning slightly west late Thursday, which increased the threat to mainland communities from flooding, tornadoes and intense winds.
Arthur prompted a hurricane warning from the southern North Carolina coast to the Virginia border. Tropical storm warnings were in effect for coastal areas as far north as Cape Cod, Massachusetts. A tropical storm watch was in effect for Nova Scotia in Canada.
Arthur forced thousands of vacationers in North Carolina to abandon their Independence Day plans, while cities farther up the U.S. East Coast rescheduled fireworks displays threatened by the storm.
The annual Boston Pops Fourth of July concert and fireworks show, one of the signature events of America's Fourth of July holiday, was rescheduled for Thursday because of potential heavy rain, while fireworks displays in New Jersey and Maine were postponed until later in the weekend.
Up to more than 22,000 were without power across the Carolinas early Friday, according to Duke Energy's website.
"We're most concerned about flooding inland and also storm surges in our sounds and our rivers further inland," North Carolina Gov. Pat McCrory said Thursday.
Before the storm hit, North Carolina tourism officials had expected 250,000 people to travel to the Outer Banks for the holiday weekend.
After passing over North Carolina early Friday, Hurricane Arthur was expected to weaken as it travelled northward and dump rain along the East Coast.
As of 7 a.m. EDT (1200 GMT) Friday, Arthur was centred about 65 miles (105 kilometres) east-northeast of Kitty Hawk, North Carolina, and 95 miles (152 kilometres) east-southeast of Norfolk, Virginia. It was moving northeast near 23 mph (37 kph).