Hurricane Joaquin gained strength Wednesday as it headed toward the Bahamas with powerful winds and torrential rain, the US National Hurricane Center said.
It was packing maximum sustained winds of 80 miles (130 kilometers) per hour, located about 215 miles east-northeast of the island chain.
At 1100 GMT, the Category One storm was moving southwestward at six miles per hour.
The Bahamas issued a hurricane warning for people to brace for heavy winds and rains.
The NHC said the eye of the storm was expected to move near or over the central Bahamas later Wednesday and Thursday.
The storm will continue to strengthen and move toward the Bahamas, but forecasters expect it will then turn north and move along the US East Coast.
But it is not yet clear if it will hit US beaches or turn back toward the Atlantic, the center said.
In any case, over the next few days Joaquin could become a major hurricane, it added.
Joaquin is expected to bring heavy rainfall of up to 20 inches (51 centimeters) over San Salvador and Rum Cay through early Friday. Precipitation of up to 10 inches is forecast over other parts of the central Bahamas.
The islands could also face flooding in coastal and maritime areas and life-threatening surf and rip currents, according to the NHC.
Joaquin is the third hurricane of the 2015 Atlantic season, which began in June and ends in November.