By Laila Kearney

NEW YORK (Reuters) - Hermine, a storm that raked Florida with hurricane-force winds last week, drifted far off the U.S. East Coast on Monday, sparing the Middle Atlantic states but forcing some beach closures.

Hermine is expected to begin weakening on Monday night as it moves northwest and then "meander slowly" off the New England coast into Wednesday, the National Weather Service said.

Forecasters warned swimmers and boaters along the Eastern Seaboard to stay out of treacherous waters and rough surf churned up by the storm.

On Cape Cod and its islands, high surf and wind put a crimp in the Labor Day plans of many people looking to celebrate summer's end, but some beaches farther south reopened.

New York City said all public beaches would be closed through Tuesday because of "life threatening" rip currents generated by Hermine.

Hermine was classified as a Category 1 hurricane when it slammed into Florida's Gulf Coast on Friday. It became a post-tropical storm by week's end after its winds dropped below 74 miles per hour (119 kph) and it lost its tropical characteristics.

The storm, which crossed northern Florida and then moved up the Georgia and the Carolina coasts, was packing sustained surface winds of up to 70 mph (110 kph) with higher gusts, the National Weather Service said.

Its strongest winds were extending outward by about 230 miles (370 km), short of U.S. shores.

"Just because it's a post-tropical cyclone doesn't mean the impact of tropical force winds, winds in general and storm surge go away," said National Hurricane Center spokesman Dennis Feltgen.

The storm has claimed at least three lives, in Florida and in North and South Carolina. The third reported death was that of a man struck by a car on a South Carolina highway on Friday as he tried to move a fallen tree, a Colleton County fire department spokesman said.

Hermine was forecast to bring up to 2 inches (5 cm) of rain to Rhode Island and southern Massachusetts through Wednesday.

A tropical storm warning remained in effect from the eastern end of New York's Long Island and to Martha's Vineyard and Nantucket Island off Massachusetts.

At least one ferry operator on Monday canceled some trips to Nantucket, which reported winds of up to 39 mph (63 km), because of the storm. "We are taking it trip by trip at this time," Hy-Line Cruises said in a Twitter message.

On Block Island off Narragansett, Rhode Island, people appeared to be taking the unsettled weather in stride, even though it kept many tourists away.

"Windy & cloudy on #BlockIsland after windy & brilliant yesterday. No ferries. Island deserted. Almost ideal. (Unless you own a business)," Twitter user Tom Anderson said.

Storm-surge inundation levels of no more than one to three feet (30 cm to 1 m) were expected in coastal areas.

As the threat to New Jersey waned, Governor Chris Christie ordered Island Beach State Park reopened for Monday.

At 5 p.m. EDT on Monday, Hermine's center was about 175 miles (285 km) southeast of the eastern tip of Long Island. It was expected to move northwest at about 7 mph (10 kph).

Hermine became the first hurricane to make landfall in Florida in 11 years, packing winds of 80 mph (130 kph), and knocking out power to 300,000 homes and businesses.

(Additional reporting by Frank McGurty in New York and Ian Simpson in Washington; Editing by Steve Orlofsky and Sandra Maler)