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.

After passing over or near North Carolina early today, Hurricane Arthur was expected to travel northward, slinging rain along the East Coast.

Forecasters have issued tropical storm warnings for Nantucket Island and parts of Cape Cod in Massachusetts as the storm approaches. A forecast map from the National Hurricane Center in Miami indicates that the center of the storm isn’t likely to pass New England until late today or early Saturday.

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 and Maine were postponed until later in the weekend.

Forecasters expect Arthur to strengthen to a Category 2 storm with winds of 96 mph or more by the time it passes over or near the 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.

The departures of vacationers left things “pretty dead” on Hatteras Island during the normally bustling run-up to the holiday weekend.

Before the storm formed, tourism officials had expected 250,000 people to travel to the Outer Banks for the holiday. Gov. Pat McCrory sought to strike a balance between a stern warning to vacationers and optimism that part of the busy weekend could be salvaged.

“Of course, this holiday weekend, the July 4th weekend, is one of the biggest weekends for coastal tourism in the state, and we anticipate a beautiful weekend after the Tropical Storm Arthur or the Hurricane Arthur is out of North Carolina,” he said.

Arthur, the first named storm of the Atlantic season, prompted a hurricane warning for much of the North Carolina coast. Tropical storm warnings were in effect for coastal areas in South Carolina and Virginia and as far north as Cape Cod, Massachusetts. On the Outer Banks’ Ocracoke Island, accessible only by ferry, a voluntary evacuation was underway. Officials said ferry service would end at 5 p.m.

Among those leaving the island was the Unmussig family of Midlothian, Va. They cut their vacation short by two days when the left Thursday morning in an SUV towing a trailer filled with bicycles and kayaks.

“Our cottage was right on the sound and we didn’t want that back current surge coming in and flooding us out,” said Donald Unmussig, 50.

“I just didn’t want to risk getting caught there. I have to work Monday morning. I didn’t want to be late,” he added. “We just decided to cut the losses and go home and not have to deal with the problems.”

On Thursday afternoon, Arthur was centered about 185 miles southwest of Cape Hatteras and moving north around 13 mph with maximum sustained winds of 90 mph.

If Arthur makes landfall today, it would be the first hurricane to do so on July Fourth, according to National Hurricane Center research that dates 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. “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.”