"Data from the Hurricane Hunters aircraft indicate that maximum sustained winds have increased to near 100 mph (160 km/h) with higher gusts," the NHC said. "Additional strengthening is forecast during the next 36 hours, and Humberto is expected to become a major hurricane by tonight or Wednesday morning."
The latest forecast track has Humberto approaching Bermuda Wednesday night, the NHC said.
Bermuda, a popular tourist destination known for its pink sand beaches, is a self-governing UK territory that lies well north of the Caribbean, about 650 miles east from the North Carolina coast.
Earlier this week, the NHC warned that Humberto could become a hurricane. Media reports said that the Bahamas felt the impact of Humberto, with small airports temporarily shuttered, and some locals briefly seeking shelter. The tropical islands are still recovering from the aftermath of powerful Category 5 Hurricane Dorian that devastated local infrastructure, killing dozens of people and leaving some 70,000 homeless.