1856 Atlantic hurricane season

The 1856 Atlantic hurricane season was a deadly Atlantic hurricane season that featured six tropical cyclones. The first system, 1856 Last Island hurricane, was first observed in the Gulf of Mexico on August 9. The final storm, Hurricane Six, was last observed on September 22. These dates fall within the period with the most tropical cyclone activity in the Atlantic. The season also had an accumulated cyclone energy (ACE) rating of 48.96. Only two tropical cyclones during the season existed simultaneously. Five of them struck land, while one of the cyclones has only a single known point in its track due to a sparsity of data. Operationally, another tropical cyclone was believed to have existed in the Wilmington, North Carolina, area in September, but HURDAT – the official Atlantic hurricane database – excludes this system. Another tropical cyclone that existed over the Northeastern United States in mid-August was later added to HURDAT.

Four tropical cyclones reached hurricane status, including two which became major hurricanes, Category 3 or higher on the modern-day Saffir–Simpson hurricane wind scale. However, in the absence of modern satellite and other remote-sensing technologies, only storms that affected populated land areas or encountered ships at sea are currently known, so the actual total could be higher. An undercount bias of zero to six tropical cyclones per year between 1851 and 1885 has been estimated. The strongest cyclone of the season struck Louisiana at peak intensity, with sustained winds of 150 mph (240 km/h). This was the strongest hurricane, in terms of sustained winds, to strike the state until Laura and Ida tied it in 2020 and 2021 respectively. It also - the 1856 Last Island hurricane - brought devastation to southern Louisiana. At least than 400 people were killed after a storm surge submerged Last Island, making it one of the deadliest hurricanes in Louisiana history. Hurricane Two brought heavy rains and squalls to Barbados and Grenada, causing "considerable" damage. Tropical Storms Three and Four had a minor impact on the Northeastern United States and Cuba, respectively. Additionally, Hurricane Five caused four deaths in Inagua, Bahamas and had a minor impact on Cuba and the United States.