Helene became a hurricane again Saturday as it moved quickly over the open Atlantic, and the storm will likely create hazardous surf conditions for Bermuda, forecasters said.

Helene's top sustained winds strengthened to 90 mph, above the 74 mph threshold to be classified as a hurricane, the National Hurricane Center in Miami said in a special advisory. Helene had been downgraded to a tropical storm with winds of 70 mph Friday night.

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However, Helene was expected to weaken as it gradually loses tropical characteristics, the hurricane center said.

Tropical storm force winds of at least 39 mph extend up to 345 miles from Helene's center.

Although the hurricane was not expected to make landfall, Bermuda was expected to have hazardous surf conditions until Saturday night, said Stacy Stewart, a senior hurricane specialist.

At 5 p.m. EDT, Helene was centered about 945 miles west of the Azores. It was moving east-northeast near 22 mph.

The Atlantic hurricane season began June 1 and ends Nov. 30. September is traditionally one of the busiest months of the season.