Hurricane Maria (search) slowly intensified Monday over warm water far out in the open Atlantic, but it was a threat only to shipping interests, forecasters said.

The storm was centered 475 miles east of Bermuda (search) at 11 a.m. EDT, the National Hurricane Center said. It was moving north at 8 mph and forecasters said gradual turns to the north and northeast would keep Maria well to the east of Bermuda.

Its top sustained wind speed was approaching 100 mph, up from 90 mph in the early morning, and the system was expected to continue strengthening until it is sapped of its strength when it reaches cooler water later in the week.

Maria is the fifth hurricane and 13th named storm of the Atlantic hurricane season, one of the busiest on record. Historically, only about four or five named storms form by this time of year, according to the hurricane center. Peak storm activity typically occurs from late August through mid-September.