Hurricane Joaquin is strengthening as it heads toward the Bahamas, causing powerful winds and torrential rain.
The US National Hurricane Center said on Wednesday that the storm was packing maximum sustained winds of 130km/h, located about 345km east-northeast of the island chain.
At 1100 GMT the category-one storm was moving southwest at 10km/h.
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 on 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.
It is not yet clear if it will hit US beaches or turn back toward the Atlantic, the centre 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 51cm over San Salvador and Rum Cay through early on Friday.
It is the third hurricane of the 2015 Atlantic season, which began in June and ends in November.
But the most destructive weather pattern so far this year was Tropical Storm Erika, which killed about 30 people and caused extensive damage in August on the small Caribbean island of Dominica.