Fast-moving fires spread by shifting winds forced thousands more to evacuate their homes on Saturday as the death toll over the week rose to 40, with hundreds missing.
The death toll from raging California wildfires rose to 31 on Thursday as body recovery teams used cadaver dogs to locate victims, making it the deadliest series of blazes in the state's history.
The National Hurricane Center forecast potentially deadly storm surges - water driven ashore by the winds along some parts of the coast.
Irma was about 495 miles (795 km) southeast of Miami, Florida, early on Friday, after soaking the northern coasts of the Dominican Republic and Haiti and pummelling the Turks and Caicos Islands.
The eye of the rare Category Five storm made landfall on Barbuda -- part of the twin island nation of Antigua and Barbuda -- just before 0600 GMT with winds gusting at up to 185 mph (295 kph), the National Hurricane Center said.
Hurricane warnings and watches were in effect for territories that dot the West Indies, including parts of the Leeward Islands, the British and US Virgin Islands and Puerto Rico.
Typhoon Hato left five dead in the gambling hub of Macau on Wednesday as it brought chaos and destruction to the enclave after sweeping through neighbouring Hong Kong, where one man also died.