1900 Galveston hurricane
The Great Galveston Hurricane, known regionally as the Great Storm of 1900, was the deadliest natural disaster in United States history, one of the deadliest hurricanes (or remnants) to affect Canada, and the fourth-deadliest Atlantic hurricane overall. The hurricane left between 6,000 and 12,000 fatalities in the United States; the number most cited in official reports is 8,000. Most of these deaths occurred in the vicinity of Galveston after storm surge inundated the entire island with of water. In addition to the number killed, every house in the city sustained damage, with at least 3,636 destroyed. Approximately 10,000 people in the city were left homeless, out of a total population of nearly 38,000. The disaster ended the Golden Era of Galveston, as the hurricane alarmed potential investors, who turned to Houston instead. The Gulf of Mexico shoreline of Galveston island was subsequently raised by and a seawall erected.
1840–49 Atlantic hurricane seasons
The Great Havana Hurricane of 1846. October 5–15.
In October, a major hurricane, likely a Category 5, moved through the Caribbean Sea. This Great Havana Hurricane struck western Cuba on October 10. was the most intense tropical cyclone in recorded history for 78 years and the first known Category 5-strength hurricane to strike Cuba. Unusual in many aspects, the 1846 Havana hurricane was the most intense of its time. Though atmospheric pressure readings in Cuba reached as low as 916 mbar. Although no reliable wind measurements were available at the time, a separate study also estimated that it produced Category 5-strength winds. In Cuba, the storm caused hundreds of deaths, capsized dozens of ships, obliterated buildings, uprooted trees, and ruined crops. Many towns were wholly destroyed or flattened and never recovered, while others disappeared entirely.
It hit the Florida Keys on October 11, destroying the old Key West lighthouse, the Sand Key Light, and Fort Zachary Taylor. In Key West, widespread destruction was noted, with 40 deaths, many vessels rendered unfit, and widespread structural damage, with all but eight of the 600 houses in Key West damaged or destroyed. Water rose to about 8 feet in lower streets. Few supplies arrived in the following days and relief efforts were gradual, with few resources within the town's vicinity. The hurricane was so destructive that years afterward, greenery on the key was sparse, and little native vegetation existed. Signs of ecological damage remained even in the early 1880s. The hurricane then headed northward, and on October 13 and hit Tampa Bay as a major hurricane. As it approached, it sucked the water out of the bay, causing the Manatee River to be so low that people walked horses across it. The hurricane moved across Florida, and remained inland over Georgia, South Carolina, North Carolina. It moved up the Chesapeake Bay, causing extensive damage through Virginia, Maryland, Washington D.C., and Pennsylvania. Some disputed reports say that at least 600 were killed; however, the official death report from Cuba says 163 deaths and damage throughout the areas it affected. 
October 10–13.
A hurricane hit Tobago on October 11, resulting in 27 casualties.