KILL DEVIL HILLS, N.C. - A strengthening Hurricane Arthur forced thousands of vacationers on the North Carolina coast to abandon their Independence Day plans while cities farther up the East Coast rescheduled fireworks displays threatened by rain from the storm.

Arthur strengthened to a Category 2 hurricane Thursday night, with winds of 100 mph as the storm neared North Carolina. Little change was expected in the storm's strength Thursday night and Friday, and Arthur was expected to weaken as it travels northward and slings rain along the East Coast.

The annual Boston Pops Fourth of July concert and fireworks show was rescheduled for Thursday because of potential heavy rain from Arthur, while fireworks displays in New Jersey, Maine and New Hampshire were postponed until later in the weekend.

In the Lowcountry, the storm sparked a high-wind advisory, riptide warnings and sizable swells, which entertained Charleston-area surfers. The cautions were all called off by early Thursday night.

Either later Thursday or early Friday, Arthur was expected to pass over or near North Carolina and its Outer Banks - a 200-mile string of narrow barrier islands with about 57,000 permanent residents.

"We don't know for sure if the exact center of Arthur is going to pass over land or not. The chances have been increasing for that to occur with the last couple of forecasts. But even if the exact center doesn't go over you, you will experience impacts tonight. The weather is going downhill in North Carolina, even as we speak," said Rick Knabb, the director of the U.S. National Hurricane Center in Miami.

The islands are susceptible to high winds, rough seas and road-clogging sands, prompting an exodus that began Wednesday night.

However, Independence Day was expected to be a sunny affair in Charleston. Forecasters called for highs in the 90s, clear skies and no chance of rain.

Among the tourists leaving Hatteras Island were 27-year-old Nichole Specht and 28-year-old Ryan Witman of Lancaster, Pa. The couple started driving at 3:30 a.m. Thursday on North Carolina Highway 12, the only road on and off Hatteras.

"We were just saying we were really, really lucky this year that the weather was so great, and then this," Specht said as she ended a two-week vacation.

Many island residents, meanwhile, decided to ride out the powerful storm rather than risk losing access to homes connected to the mainland by a highway prone to washouts.

"All the people that I know who live here are staying put," said Mike Rabe, who planned to stay in his Rodanthe home despite an evacuation order for surrounding Hatteras Island.

On the Isle of Palms Thursday morning, surfer Laurie Ulmer estimated there were 6-to 8-foot waves.

The 52-year-old Sullivan's Island resident squeezed in a few sets before heading to work. "It's been flat all year until now," Ulmer said. "There's a bad rip current, but it's nice."

Those rip currents were dragging surfers quickly southward from the Isle of Palms Pier. By the time he caught two waves, Ulmer said, they had swept him from the pier to Coconut Joe's restaurant.

"I wasn't sure if it was a hurricane," he said. "I just saw the surf conditions and came out. ... I'll be back after work."

Casey Glowacki, a Mount Pleasant restaurateur who owns Sesame Burgers and Beer and Five Loaves Cafe, also spent the morning on a surfboard instead of in the office.

He spoke in knee-deep water as the skies opened up and began to pour. Under the ocean's surface, murky water tugged at his legs.

"It's drifty, big currents and fun waves," Glowacki said. "It's just pulling you down the beach.

"But you've got to take it when you can get it in South Carolina."

Tropical storm warnings also were in effect for the coastal areas of Virginia and as far north as Cape Cod, Mass.

On the Massachusetts island of Nantucket, no evacuations were planned, but residents who have lived through many a fierce storm said they know better than to totally relax.

"I think that for the most part it's another storm, but you never know what can happen," said Rocky Fox, who owns the Chicken Box nightclub on Nantucket. "Being the Fourth of July weekend, things seems to be magnified."

Fox said Nantucket residents are used to being prepared. "Mother Nature was upset with us this winter, and she may not be through. We're on an island. You can never tell what it's going to do. You prepare for the worst and hope for the best."

By Thursday night, Arthur was centered about 35 miles east of Cape Fear, North Carolina, and 140 miles southwest of Cape Hatteras and moving north around 15 mph with maximum sustained winds of 90 mph.

If Arthur makes landfall in the U.S. on Friday, it would be the first hurricane to do so on July Fourth, according to National Hurricane Center research that goes back to the 1850s.

Among the residents planning to ride out the storm was 79-year-old Tom Murphy, a retired Presbyterian minister who has lived on Hatteras Island since 1986.

"There are some concerns," he said, particularly about the coastal highway N.C. 12. "But they are not enough to outweigh the desire to be here when it's all over. The awful part about leaving is the wondering what's happening at your house down there when you can't get back."

Bo Petersen and Andrew Knapp of the Post and Courier contributed to this report.