Officials in Bermuda urged residents to "prepare for the worst" as Hurricane Leslie headed toward the British territory, bringing with it powerful winds and heavy rain.
Meanwhile, the Category 1 storm's effects were already being felt as far away as the U.S. East Coast, where forecasters issued warnings for life-threatening rip currents spawned by the distant storm.
In Bermuda, schools prepared to close Friday as residents got ready for the approaching storm. Government offices will close at 3 p.m. Friday.
"Leslie could be a historic storm for Bermuda as it is very large and forecast to intensify rapidly as it approaches," Bermuda's Emergency Measures Organization said in a statement. "The island could experience hurricane force winds for a sustained period of time, possibly up to two days."
The agency said the storm is expected to pass close by the island early Sunday, though its path was uncertain. The territory's weather service expects Leslie's winds to exceed 90 mph at that point.
The hurricane seemed to stall Thursday, the U.S. National Hurricane Center said. The storm was about 430 miles south-southeast of Bermuda, and was stationary, the center said in an afternoon statement.
It had maximum sustained winds of 75 mph (121 kph), the hurricane center said.
The storm wasn't expected to move much until Friday, when it likely will strengthen, the center said. Bermuda was under a tropical storm watch.
Wayne Perinchief, Bermuda's national security minister, said officials are planning a "well-coordinated" response to any problems caused by the storm.
The storm is already dishing out heavy swells and dangerous currents in coastal areas of Bermuda, the Leeward Islands, Puerto Rico, the Virgin Islands and the U.S. East Coast from Florida to New York, the National Weather Service said.
Forecasters warned of potentially deadly rip currents that can pull even the strongest swimmers out to sea quickly. The agency warned beachgoers to stay out of the surf until the danger passes.
The U.S. Coast Guard also warned boaters to use "extreme caution" through the weekend along the East Coast.
Another hurricane, Michael, formed late Wednesday in the eastern Atlantic. By Thursday, it had become the first major hurricane of the season as it strengthened to a Category 2, with winds of near 110 mph.
Michael is the seventh hurricane of the 2012 season, but posed no immediate threat to land, the hurricane center said.