Hurricane Frederic was an intense and damaging tropical cyclone that carved a path of damage from the Lesser Antilles to Quebec, in particular devastating areas of the United States Gulf Coast. Though only five were killed directly, the US$1.77 billion (equivalent to $5.1 billion in 2019) in damage accrued by Frederic made it the Atlantic basin's costliest tropical cyclone on record at the time. Prior to its final landfall, the threat that Frederic imposed on areas of the U.S. Gulf Coast triggered a mass exodus from the region larger than any other evacuation in the past. While the storm primarily impacted the U.S. states of Mississippi and Alabama, lesser effects were felt throughout the Greater and Lesser Antilles, as well as inland North America.

Frederic developed from a tropical depression south of the Cape Verde Islands on August 28, 1979.

Tracking at a steady clip westward, the primitive cyclone reached tropical storm intensity the next day. Favorable conditions in the open Atlantic allowed for Frederic to reach hurricane intensity on September 1. However, outflow from nearby Hurricane David began to inhibit further intensification and would continue to do so for roughly a week, weakening Frederic as it tracked across the Greater Antilles. The tropical cyclone nearly dissipated over Cuba before redeveloping on September 9 near the Isle of Youth. From then on, Frederic moved northwestward, intensifying to its peak intensity in the Gulf of Mexico with winds of 130 mph (210 km/h) on September 12, shortly before making landfall at Dauphin Island, Alabama just below the state line between Alabama and Mississippi. Over the United States, Frederic weakened for a final time before becoming extratropical in Pennsylvania on September 14 and dissipating the next day.

Damage estimates vary due to inadequate reporting of private insurance claims as well as lack of hard data on uninsured damage; Frederic is believed to have inflicted $5 million (1979 USD) in both Puerto Rico and the U.S. Virgin Islands, with an additional $1.7 billion in damage on the mainland United States. FEMA, which had been established only three months before Frederic hit, was the focal point for nearly $250 million in federal aid for recovery, $188 million of which went to Alabama (1979 USD). In southern Alabama, the landscape was changed for years, with thousands of tall pine trees tilted and leaning northwest.