Hurricane Harvey was a devastating tropical cyclone that made landfall in Texas and Louisiana in August 2017, causing catastrophic flooding and more than 100 deaths. It is tied with 2005's Hurricane Katrina as the costliest tropical cyclone on record, inflicting $125 billion (2017 USD) in damage, primarily from catastrophic rainfall-triggered flooding in Greater Houston and Southeast Texas; this made the storm the costliest natural disaster recorded in Texas at the time. It was the first major hurricane to make landfall in the United States since Wilma in 2005, ending a record 12-year span in which no hurricanes made landfall at the intensity of a major hurricane throughout the country. In a four-day period, many areas received more than 40 inches (1,000 mm) of rain as the system slowly meandered over eastern Texas and adjacent waters, causing unprecedented flooding. With peak accumulations of 60.58 in (1,539 mm), in Nederland, Texas, Harvey was the wettest tropical cyclone on record in the United States. The resulting floods inundated hundreds of thousands of homes, which displaced more than 30,000 people and prompted more than 17,000 rescues.

The eighth named storm, third hurricane, and first major hurricane of the extremely active 2017 Atlantic hurricane season, Harvey developed from a tropical wave to the east of the Lesser Antilles, reaching tropical storm status on August 17. The storm crossed through the Windward Islands on the following day, making landfall on the southern end of Barbados and a second landfall on Saint Vincent. Upon entering the Caribbean, Harvey began to weaken due to moderate wind shear, and degenerated into a tropical wave north of Colombia, late on August 19. The remnants were monitored for regeneration as it continued west-northwestward across the Caribbean and the Yucatán Peninsula, before redeveloping over the Bay of Campeche on August 23. Harvey then began to rapidly intensify on August 24, regaining tropical storm status and becoming a hurricane later that day.

While the storm moved generally northwest, Harvey's intensification phase stalled slightly overnight from August 24–25; however, Harvey soon resumed strengthening and quickly became a Category 4 hurricane later that day with peak 1-minute sustained winds of 130 mph. Hours later, Harvey made landfall at San José Island, Texas, at peak intensity, followed by another landfall at Holiday Beach at Category 3 intensity. Rapid weakening then ensued, and Harvey had downgraded to a tropical storm as it stalled near the coastline, dropping torrential and unprecedented amounts of rainfall over Texas. On August 28, the storm emerged back over the Gulf of Mexico, strengthening slightly before making a fifth and final landfall in Louisiana on August 29. As Harvey drifted inland, it quickly weakened again as it became an extratropical cyclone on September 1, before dissipating two days later.

In addition to the huge cost and extent of the damage it caused, Harvey caused at least 107 confirmed deaths: 1 in Guyana and 106 in the United States. Due to the extensive damage, the name "Harvey" was retired in April 2018 and will not be used for another Atlantic tropical cyclone.