State officials in Florida, South Carolina and Georgia cautioned residents not to hunker down at home if they live in the hurricane's potential path.
The National Hurricane Center isn't saying that Matthew will make landfall in Florida, just that the center of the storm will get "very near" the Atlantic Coast, possibly as a Category 4 hurricane.
Florida Gov. Rick Scott warned 1.5 million residents they had 24 hours to get ready, or better yet, get going. The voluntary and mandatory evacuations included the Miami area and extended all the way north past the city of St. Augustine.
South Carolina Gov. Nikki Haley gave evacuation orders for the coastal counties of Charleston and Beaufort. An estimated 250,000 residents evacuated from Charleston and Beaufort, said Kim Stenson, the director of South Carolina Emergency Management.
North Carolina Gov. Pat McCrory declared a state of emergency for more than half the state's 100 counties; also Georgia Gov. Nathan Deal has declared a state of emergency in 30 counties on or near the Atlantic Coast.
President Barack Obama warned Americans in the storm's path to pay attention and take any evacuation orders seriously.