With maximum sustained winds of 195 kilometers per hour (kph), Katia was a "major" storm of Category 3 intensity scale five-step Saffir-Simpson.
The center of the storm was 600 kilometers south of the British colony of Bermuda, forecasters said the National Hurricane Center of the United States (CNH), based in Miami.
Katia was moving northwest and is expected to pass between Bermuda and the east coast of the United States on Wednesday and Thursday.
It is expected that the core of the storm remains over water, but Katia covered more than 640 kilometers outside and gusts and thunderstorms could reach Bermuda, forecasters warned.
The Government of Bermuda issued a tropical storm warning for the island’s 70,000 residents. Despite its small size and isolated location, the territory is a global reinsurance center.
"The strength of the winds of tropical storm, especially its bursts, may come to Bermuda on Thursday," U.S. forecasters said.
Katia was generating large waves and rip currents that threatened threatening the beaches located along the eastern United States, Bermuda, Bahamas and Greater Antilles in the northern Caribbean, the hurricane center forecasters said.
After spending Thursday midway between Bermuda and the Carolinas are expected to weaken Katia and change of direction away from the United States on a path that poses no threat to any country.