The 2005 Atlantic hurricane season was the most active Atlantic hurricane season in recorded history, shattering previous records on repeated occasions. The impact of the season was widespread and ruinous with at least 2,280 deaths and record damages of over US$100 billion. Of the storms that made landfall, five of the seven major hurricanes that did so—Dennis, Emily, Katrina, Rita, and Wilma—were responsible for most of the destruction. The Mexican states of Quintana Roo and Yucatán and the U.S. states of Florida and Louisiana were each struck twice by major hurricanes; Cuba, The Bahamas, Haiti, Mississippi, Texas, and Tamaulipas were each struck once and in each case brushed by at least one more. The most catastrophic effects of the season were felt on the United States' Gulf Coast, where a 30-foot (10 meter) storm surge from Hurricane Katrina caused devastating flooding that inundated New Orleans and destroyed most structures on the Mississippi coastline, and in Guatemala, where Hurricane Stan combined with an extratropical system to cause deadly mudslides.
The season officially began on June 1, 2005, and lasted until November 30, although it effectively persisted into January 2006 due to continued storm activity. A record 28 tropical and subtropical storms formed, of which a record fifteen became hurricanes. Of these, seven strengthened into major hurricanes, a record-tying five became Category 4 hurricanes and a record four reached Category 5 strength, the highest categorization for hurricanes on the Saffir–Simpson hurricane scale. Among these Category 5 storms were Hurricanes Katrina and Wilma, the former the costliest and the latter the most intense Atlantic hurricane on record.