Hurricane Katrina primarily struck the Gulf Coast of the United States, with the most significant impacts in Louisiana and Mississippi. The storm’s landfalls and core devastation occurred on August 29–30, 2005, after Katrina intensified over the Gulf of Mexico and then made two major landfalls: first near Buras, Louisiana, and then near the Mississippi coast (Hancock County), both as a strong hurricane. The disaster was amplified by levee breaches in the New Orleans area, leading to widespread flooding and extensive loss of life and property, especially in and around New Orleans and the nearby Mississippi coast. Note that the storm had weaker impacts in Florida earlier in its path, where it briefly made landfall in the southern part of the state as a Category 1 hurricane before moving into the Gulf of Mexico and rapidly intensifying. If you’d like, I can provide a concise, cited timeline of Katrina’s landfalls and the resulting damages.
