Forecasters have been urging people on the island to monitor the storm's progress.
As of about 5 p.m. EDT Wednesday, the center of the storm was about 560 miles northeast of the northern Leeward Islands and about 660 miles southeast of Bermuda.
Maximum sustained winds are about 105 mph with some higher gusting. National Hurricane Center forecasters expect Bertha to strengthen in the next 24 hours and it could again become a major hurricane. It had weakened to a Category 1 storm before picking up strength.
The Atlantic season's first hurricane is traveling west-northwest at about 12 mph.
