Joaquin has surged in strength to become a Category Three hurricane as it barrelled toward the Bahamas, on a track towards that could take it to the US east coast, forecasters said.
The storm, packing maximum sustained winds of 185km/h, is located about 145 kilometres east of San Salvador in the Bahamas, the Miami-based US National Hurricane Centre said.
Major hurricanes are Category Three and above, with top sustained winds of 180-210 km/h and higher.
The force of these fierce winds can tear off roofs, fell trees and wooden-frame homes, while heavy rains can cause coastal flooding and burst river banks.
At 3am (GMT), Joaquin was churning southwest at 9km/h, the centre added.
"The centre of Joaquin is expected to move near or over portions of the central Bahamas tonight and Thursday, and be near or over portions of the northwestern Bahamas Thursday night or Friday," the NHC said, warning that "further strengthening is expected".
A hurricane warning, which puts people on notice to finish preparations and take cover, is in effect for central Bahamas including Cat Island, the Exumas, Long Island, Rum Cay, and San Salvador and the northwestern Bahamas including the Abacos, Berry Islands, Eleuthera, Grand Bahama Island, and New Providence, authorities said.
The hurricane centre also said Joaquin could turn north or northwest Thursday night and Friday, and move along the US East Coast.