In Alabama, residents were advised to start evacuating today and Mississippi Governor Phil Bryant is also advising residents to prepare.
"I urge Mississippians to monitor their local media and heed all warnings and evacuation orders issued by local and state officials," he said.
Airlines canceled 857 flights on Sunday, with airports in Miami and Fort Lauderdale canceling 589, according to the flight-tracking service FlightAware. There have already been 235 flight cancellations for today, with 167 in Miami alone.
ABC News' Dean Schabner and Max Golembo, ABC News Radio and The Associated Press contributed to this report.