Hurricane Michael made landfall near Mexico Beach, Fla., packing maximum sustained winds of 155 miles per hour, in the early afternoon on Wednesday.
The storm's central pressure was measured at 919 millibars, making it one of the strongest tropical cyclones to impact the mainland U.S. in history.
Hurricane and tropical storm warnings had been posted for portions of the Gulf Coast from Alabama through the entire Florida panhandle. Storm surge warnings are also in effect for parts of the Gulf Coast of Florida, as storm surge of up to 14 feet is expected in some areas.
"Michael will produce potentially catastrophic wind damage where the core of the hurricane moves onshore later today in the Florida Panhandle, with the highest risk between Apalachicola and Panama City," the National Hurricane Center said in its 11 a.m. ET forecast discussion.
The governors of Florida and Alabama declared states of emergency ahead of the storm, and mandatory and voluntary evacuations have been posted for coastal portions of the Florida panhandle. Georgia Gov. Nathan Deal declared a state of emergency for 92 counties across the southern half of the state, including Bibb and Richmond counties, which contain the cities of Macon and Augusta.
The storm is eventually expected to track across Georgia and the Carolinas before heading into the Atlantic Ocean. Heavy rain is expected in some of the same areas impacted by Hurricane Florence, with 3 to 6 inches forecast for eastern Georgia, the Carolinas and southern Virginia. Tropical storm warnings have also been issued for the North Carolina coast and continue for the coasts of South Carolina and Georgia and the east coast of Florida north of Fernandina Beach.