Hurricane Sandy (unofficially referred to as Superstorm Sandy) was the deadliest, the most destructive, and the strongest hurricane of the 2012 Atlantic hurricane season. The storm inflicted nearly $70 billion (2012 USD) in damage and killed 233 people across eight countries from the Caribbean to Canada. The eighteenth named storm, tenth hurricane, and second major hurricane of the year, Sandy was a Category 3 storm at its peak intensity when it made landfall in Cuba. While it was a Category 2 hurricane off the coast of the Northeastern United States, the storm became the largest Atlantic hurricane on record as measured by diameter, with tropical-storm-force winds spanning 1,150 miles (1,850 km).Sandy developed from a tropical wave in the western Caribbean Sea on October 22, quickly strengthened, and was upgraded to Tropical Storm Sandy six hours later. Sandy moved slowly northward toward the Greater Antilles and gradually intensified. On October 24, Sandy became a hurricane, made landfall near Kingston, Jamaica, re-emerged a few hours later into the Caribbean Sea and strengthened into a Category 2 hurricane. On October 25, Sandy hit Cuba as a Category 3 hurricane, then weakened to a Category 1 hurricane. Early on October 26, Sandy moved through the Bahamas. On October 27, Sandy briefly weakened to a tropical storm and then restrengthened to a Category 1 hurricane. Early on October 29, Sandy curved west-northwest (the "left turn" or "left hook") and then moved ashore near Brigantine, New Jersey, just to the northeast of Atlantic City, as a post-tropical cyclone with hurricane-force winds. Sandy continued drifting inland for another few days while gradually weakening, until it was absorbed by another approaching extratropical storm on November 2.In Jamaica, winds left 70% of residents without electricity, blew roofs off buildings, killed one person, and caused about $100 million (2012 USD) in damage. Sandy's outer bands brought flooding to Haiti, killing at least 54, causing food shortages, and leaving about 200,000 homeless; the hurricane also caused two deaths in the Dominican Republic. In Puerto Rico, one man was swept away by a swollen river. In Cuba, there was extensive coastal flooding and wind damage inland, destroying some 15,000 homes, killing 11, and causing $2 billion (2012 USD) in damage. Sandy caused two deaths and an estimated $700 million (2012 USD) in damage in The Bahamas.

In the United States, Hurricane Sandy affected 24 states, including the entire eastern seaboard from Florida to Maine and west across the Appalachian Mountains to Michigan and Wisconsin, with particularly severe damage in New Jersey and New York. Its storm surge hit New York City on October 29, flooding streets, tunnels and subway lines and cutting power in and around the city. Damage in the United States amounted to $65 billion (2012 USD). In Canada, two were killed in Ontario, and the storm caused an estimated $100 million (2012 CAD) in damage throughout Ontario and Quebec.