Retiree Barbara Richardson rode out the storm in her home in the southern parish of Warwick, where electricity was knocked out for about an hour.
"The wind was howling pretty bad there for a while, but now it's calming down," Richardson said. "We've seen worse here."
The U.S. National Hurricane Center said the center of the storm was 65 miles (100 kilometers) northeast of the Atlantic island late Monday afternoon with sustained winds near 70 mph (110 kph) and higher gusts.
Bertha is expected to strengthen into a hurricane during the next 24 hours, according to the hurricane center.
Dangerous rip currents were occurring along the U.S. East Coast from the Carolinas through southern New England, according to the hurricane center. Officials said that may have contributed to at least one drowning Saturday along a New Jersey beach.
Bertha was swirling north at near 9 mph (15 kph). It was expected to bring 3-5 inches (8-13 centimeters) of rain to Bermuda. A turn to the northeast was expected Tuesday, with a turn to the east expected Wednesday.
Bertha became the Atlantic season's first hurricane on July 7.
Meanwhile, Elida became the second hurricane of the Eastern Pacific region's season, scattering rains across Mexico's central coast.
But the weakening storm, with winds of nearly 85 mph (140 kph), was headed away from land.
Elida was centered about 490 miles (790 kilometers) south of the southern tip of the Baja California peninsula and it was moving west at near 10 mph (17 kph).
