The National Hurricane Center downgraded Irma to a Category 4 storm early Friday but it remains ‘extremely dangerous.’
‘Life-threatening inundation’ is still likely in the low-lying isolated Florida Keys as it barrels toward the US mainland.
Four Southeast states have now issued states of emergency.
"The core of the hurricane will move between the north coast of Cuba and the Bahamas during the next day or two and be near the Florida Keys and the southern Florida Peninsula Sunday morning," it said, as it hit Turks and Caicos early Friday.
Meteorologists say Irma is probably unlikely to strengthen again to a Category 5 but it will almost certainly now make landfall in Florida.
More than half a million residents are facing evacuation in Florida, Georgia, South Carolina and North Carolina.
So far at least 18 people have died across the Caribbean region but that could well be higher as some areas are still cut off without infrastructure and power.
When it eventually arrives in Florida, up to 10 feet of storm surge is expected.
Meanwhile Prime Minister of Barbuda Gaston Browne said most buildings are now ‘rubble’ with more than half of its population homeless.
Antigua and Barbuda is bracing for more misery with Category 2 Hurricane Jose heading that way in the coming days.
