The warnings stretched from east of Morgan City, La. -- which includes the New Orleans area -- to Destin, Fla.
Isaac lashed the Florida Keys as a tropical storm on Sunday, bringing rain and strong winds. But residents for the most part took it in stride. However, preparations have begun farther north as forecasters warn Isaac could be a strong Category 2 hurricane by the time it reaches the Gulf Coast.
The U.S. National Hurricane Center in Miami says Isaac is expected to hit somewhere between southeastern Louisiana and the Florida Panhandle either late Tuesday or early Wednesday.