MIAMI — Tropical Storm Sean strengthened as it moved over the Atlantic toward Bermuda on Thursday, kicking up choppy surf and gusty winds on the British island.

The U.S. National Hurricane Center in Miami said Sean had maximum sustained winds of 65 mph. It was about 285 miles west-southwest of Bermuda and moving northeast at 13 mph. The storm’s center was expected to pass northwest of Bermuda on Friday morning.

A tropical storm warning was in effect for Bermuda, with storm conditions predicted to begin Thursday night. Sean was expected to produce 1 to 3 inches of rainfall there.

Swells generated by the storm also were affecting the southeastern U.S. coast with life-threatening surf and rip currents.

Sean’s approach caused little anxiety on Bermuda. There was no sign of anyone lining up for storm supplies in shops and most people went about their day normally.

Jane Davis, a 36-year-old office worker who lives in Southampton parish, said the forecast would not disrupt her routine.

“I have no concerns about the tropical storm. It’s business as usual for me. I will go out for a run even if the winds pick up and it starts raining,” she said.

Mark Guishard, director of the Bermuda Weather Service, said its forecast called for some gusty winds, rain and thunderstorms overnight.

Authorities urged islanders to pick up debris and secure potted plants, garbage bins and other lawn items that high winds could blow about. But the government said a causeway linking the island’s east end to the rest of Bermuda would not close.

The Atlantic hurricane season lasts from June to the end of November.