The Miami-based National Hurricane Center (NHC) warned that Bermuda could be hit with tropical storm force winds and up to three inches of rain by Wednesday, and was at risk of life-threatening waves and tides.
The center of the hurricane is expected to approach the archipelago Wednesday night, the NHC said, and current tracks show it side-swiping Bermuda's west coast Thursday.
Packing 90 mph (150 kph) winds early Tuesday morning, Humberto was 570 miles (920 km) west of Bermuda, picking up speed and moving at 8 mph (13 kph), the forecasters said.
After gaining hurricane strength late Sunday, Humberto dropped another 2 inches of rain on the storm-ravaged northwestern Bahamas as it churned away from the U.S. coast, the NHC said.
It is bringing life-threatening waves and tides to parts of the U.S. east coast from Central Florida to North Carolina and dangerous conditions will remain for the next few days, forecasters said.