Hurricane Erin is growing larger, and its expected impact is likely to stretch far beyond its footprint.

On Monday morning, the storm’s eye was already over 35 miles in diameter, and the tropical-storm-force winds (39 miles per hour or higher) spinning around it stretched 230 miles from the center. Typically, a hurricane has tropical-force winds that extend about 150 miles outward; Erin is almost double that and still growing in size, according to the National Hurricane Center.

Even though the hurricane is far from shore, the storm’s edges may still scrape a portion of the Carolinas, and rip currents could create beach hazards along the East Coast from Florida to Canada. Although the storm is still most likely to pass through the open sea between Bermuda and the East Coast of the United States, the latest forecast has nudged it slightly farther west, prompting new concerns about how widespread its effects could be, even as it remains far from land.

The authorities in Hyde County, N.C., declared a state of emergency for Ocracoke Island on Sunday night and ordered people to leave. Officials there said that even though Hurricane Erin was expected to stay well off their coast, it could still produce dangerous waves more than 20 feet high, which could possibly inundate protective dune structures along the highway.

They said that portions of Highway 12 on Ocracoke Island would likely be impassable for several days.

On Monday morning, hundreds of tourists were leaving Ocracoke, a small coastal community that is only reachable by boat. It is packed with visitors in the summertime.

Meteorologists — and the computer models they use — remain confident that the storm will curve away from its closest point to the East Coast by the middle of the week. But any farther shifts to the west would put the North Carolina coast, especially the Outer Banks, at greater risk for tropical stormlike conditions and possibly some hurricane-force wind gusts.

“Interests along the Outer Banks of North Carolina and Bermuda should monitor the progress of Erin, as there is a risk of strong winds associated Wednesday with the outer rain bands during the middle part of the week,” forecasters with the Hurricane Center wrote late Monday morning.

North Carolina juts out into the Atlantic just enough to make it prone to hurricanes, or to a glancing blow as one passes by, as in the case of Erin. Over the years, the Outer Banks have endured significant damage from rising sea levels and large storm swells like those from Erin.

“Confidence in hazardous conditions has increased,” forecasters with the National Weather Service on the Outer Banks wrote on Monday morning.

How rip currents bring danger even far from a storm

A large swell is forming beneath Erin; the water’s energy will pulse toward the East Coast. When it hits the coast, that energy must go somewhere, often straight back out to sea in the form of a powerful rip current. This can happen in knee-deep water and usually in an area of the beach that looks calmest, as the outgoing water can knock down incoming waves. Rip currents are the third-highest cause of death related to hurricanes.

Storms remaining far out at sea, like Erin, can still affect large parts of the eastern seaboard, which is densely populated.

In 2008, Hurricane Bertha was more than 1,000 miles offshore, but it caused rip currents that resulted in three deaths along the New Jersey coast and led to 1,500 lifeguard rescues in Ocean City, Md., over a single week, according to data from the Hurricane Center.

A storm moving generally parallel to the East Coast can lead to rip currents from Miami up into the Northeast and Atlantic Canada. Warnings for the increased risk of rip currents have already been issued for the entire East Coast of the United States for the next few days.

When a storm is closer to shore, there’s often lightning, rain and angry seas with wind-driven sand. “Any reasonable person might conclude that it’s unsafe to be outside in these conditions,” said Jaime Rhome, the deputy director of the Hurricane Center. But when the storm is farther away, there are fewer visual clues that something is wrong. This week, beaches could be sunny and warm with blue skies, giving no indication that it might be unsafe to enter the ocean.

Experts recommend swimming in areas with lifeguards and paying attention to beach warning flags for safety cues.