Hurricane Katrina was a devastating and deadly Category 5 Atlantic hurricane that caused 1,836 fatalities and damages estimated between $97.4 billion to $145.5 billion in late August 2005, particularly in the city of New Orleans and its surrounding area. At the time, it was the costliest tropical cyclone on record, later tied by Hurricane Harvey in 2017. Katrina was the twelfth tropical cyclone, the fifth hurricane, and the third major hurricane of the 2005 Atlantic hurricane season. It was also the fourth-most intense Atlantic hurricane to make landfall in the contiguous United States, gauged by barometric pressure.

The Gulf of Mexico is an ocean basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States; on the southwest and south by the Mexican states of Tamaulipas, Veracruz, Tabasco, Campeche, Yucatán, and Quintana Roo; and on the southeast by Cuba. The Southern U.S. states of Texas, Louisiana, Mississippi, Alabama, and Florida, which border the gulf on the north, are often referred to as the "Third Coast" of the United States.