Florida Gov. Rick Scott has already declared a state of emergency, and last night more than 100,000 Miami-Dade residents in Miami Beach and low-lying mainland areas were instructed to leave their homes by Miami Mayor Carlos Gimenez, who issued his first evacuation order.
Now, FEMA Chief Brock Long says that the storm will have a "truly devastating" impact when it slams into southern coastal areas of the US, adding that people in Florida and other states must heed evacuation orders after the storm killed more than 10 people in the Caribbean.
"Bottom line is the majority of people along the coast have never experienced a major hurricane like this. It will be truly devastating," he told CNN.
While mandatory evacuation orders have so far only been issued in parts of Florida, Brock expects similar orders to be issued for Georgia, South Carolina and North Carolina within the next 48 hours, Long said: "The entire southeastern United States better wake up and pay attention," he added.