The centre of the hurricane is located north of the northwestern tip of Haiti over the British overseas territory of Turks and Caicos.
Airports and businesses were closed on Wednesday in the Turks and Caicos, where high winds downed power lines and kicked up debris into the streets.
The State Department has issued a travel warning for the islands and the Bahamas.
Haiti, which is still rebuilding from its massive 2010 earthquake, was largely spared by the storm apart from a few mudslides on the northern coast.
Authorities in the Dominican Republic evacuated more than 11,000 people to shelters before winds hit the island’s north side on Monday.
US emergency officials warn that the entire US eastern seaboard should be on alert. Bill Read, head of the Miami-based National Hurricane Center, said that a very large storm would most likely approach the coast of South Carolina and North Carolina by Saturday. New England also risks being affected.
Federal Emergency Management Agency (FEMA) chief Craig Fugate announced to residents: “It’s critical that you take this storm seriously.”
Hurricane Irene ripped through Puerto Rico on Monday, killing one woman and displacing some 1,500 people. Nearly a million were left without electricity.
President Obama has since issued an emergency declaration for the territory.