Powerful rip currents unleashed by Hurricane Erin this week are forcing beaches from Florida to New England to close or to issue warnings that even strong swimmers who venture into the water could be swept out to sea.

The National Weather Service on Wednesday urged people not to swim at most East Coast beaches because of life-threatening surf and rip currents generated by the hurricane, which was churning over the Atlantic Ocean, 370 miles off Cape Hatteras, N.C.

The Weather Service warned of a high risk of rip currents all the way from Miami to Montauk, on the east end of Long Island in New York, with a low to moderate risk along the New England coast as far north as Camden, Maine.

Officials have banned swimming at beaches in New York City, New Jersey, Delaware and North Carolina, where Gov. Josh Stein declared a state of emergency on Tuesday, and where more than 1,000 people have evacuated the Outer Banks. Even beaches far from the brunt of the storm, in places like Scituate, Mass., have closed.

In Seaside Heights, N.J., which is usually teeming with people in late August, swimming was prohibited on Wednesday, and lifeguards were patrolling the shore to make sure no one was in the water.

“For swimming, it’s absolutely tremendously dangerous, between the storm and the northeast wind,” said Hugh Boyd, the town’s chief lifeguard. “Don’t even think about going into the ocean, even if you’re a good swimmer. This isn’t the ocean for that. We won’t let our own guards go in at this point.”