CHARLESTON, S.C. — As one of the year’s busiest travel weekends approaches, so does another visitor: Tropical Storm Arthur, expected to grow into a hurricane by the Fourth of July and hit most harshly at North Carolina’s Outer Banks.

The first named storm of the Atlantic hurricane season prompted a hurricane warning for a wide swath of the North Carolina coast and had officials, hotel owners and would-be vacationers as far north as New England watching forecasts.

Officials ordered a mandatory evacuation of Hatteras Island starting at 5 a.m. Thursday.

A voluntary evacuation was announced earlier for the Outer Banks’ Ocracoke Island, which is accessible only by ferry.

Other areas of the Outer Banks were taking a cautious, but still-optimistic approach: No evacuations had been ordered for areas north of Hatteras.

Tourism officials expect about 250,000 people to visit the Outer Banks and stay in hotels and rental homes for the long holiday weekend. “We want everybody to be safe and prepared, but we are not overly concerned at this point,” said Lee Nettles, the executive director the Outer Banks Visitors Bureau. He noted that forecasters were predicting the storm would move fast and be less severe than others in locals’ memories.

Stores saw runs on generators, lanterns and flashlights, but even some workers weren’t yet concerned.

“I’ve been through Irene. I went through Isabelle,” said Bill Motley, who has lived on the Outer Banks for 13 years. “I’m not even worried about this one. I’m more worried about my tomato plants.”

Still, Gov. Pat McCrory declared a state of emergency for 25 coastal and adjoining counties. “Don’t put your stupid hat on,” he said, as he urged surfers and swimmers not to get in the water.

On Wednesday afternoon, Arthur was 220 miles south of Charleston and moving north about 7 mph with maximum sustained winds of 60 mph. The National Hurricane Center predicted it would be a Category 1 hurricane with sustained winds of at least 74 mph either late Wednesday or on Thursday.

The forecast did not call for a landfall in the U.S., but many areas warned of upcoming rain, wind and potential rip tides.

The worst of the storm should occur at Cape Hatteras, North Carolina, about dawn Friday, with 3 to 5 inches of rain and sustained winds up to 85 mph, said Tony Saavedra, of the National Weather Service. But forecasters said that by later Friday, the effects of Arthur would be past the Outer Banks, with the rest of the weekend salvaged.

The Hurricane Center predicted the storm would be off the coast of New England later in the day and eventually make landfall in Canada’s Maritime Provinces as a tropical storm.