Isaac strengthened into the fifth hurricane of the Atlantic season Saturday, and was headed for Canada, forecasters said.

At 11 a.m. EDT, the ninth named storm of the Atlantic hurricane season had top sustained winds near 75 mph, up from 45 mph, the National Hurricane Center in Miami said.

The storm was centered about 370 miles east-southeast of Bermuda and moving northwest near 7 mph. A turn to the north-northwest was expected by Sunday.

Hurricane force winds extend 40 miles from the center, while tropical storm force winds of at least 39 mph extended up to 125 miles from Isaac's center.

Forecasters said Isaac should stay to the east of Bermuda, but the Canadian Maritimes and Newfoundland could feel the outer edges of the storm, forecasters said.

Isaac developed into a tropical storm Thursday.

The Atlantic hurricane season began June 1 and ends Nov. 30.

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