The 1870 Atlantic hurricane season lasted from mid-summer to late-fall and comprised one tropical storm and ten hurricanes, two of which became major hurricanes, (Category 3+). However, in the absence of modern satellite and other remote-sensing technologies, only storms that affected populated land areas or encountered ships at sea were recorded, so the actual total could be higher. An undercount bias of zero to six tropical cyclones per year between 1851 and 1885 and zero to four per year between 1886 and 1910 has been estimated. Season summary The Atlantic hurricane database (HURDAT) recognizes eleven tropical cyclones for the 1870 season. Ten storms attained hurricane status, with winds of 75 mph (119 km/h) or greater. Of the eleven Atlantic cyclones known for 1870 only three made landfall. Although Hurricane One caused damage in Alabama, the storm centre may not have crossed the coastline. Hurricane Nine made landfalls in both Cuba and Florida. Hurricane Two and Tropical Storm Three were both active in the first week of September but neither made landfall, although Hurricane Two did come close to the Newfoundland coastline. Later that month two more hurricanes were seen in the western Atlantic. Hurricane Four was an intense category three cyclone while Hurricane Five was a weaker category one storm. More notable was Hurricane Six. This hurricane, known as the Hurricane of San Marcos or the Straits of Florida Hurricane, caused massive flooding in Cuba and south Florida, resulting in 2,000 casualties and at least $12 million in damages. Hurricanes Seven and Eight were also active in the first half of October, both in the mid-Atlantic. Hurricane Nine made landfalls in both Cuba and Florida and was responsible for some 52 deaths. Hurricane Ten was sighted on October 23 near the Turks and Caicos Islands. The last cyclone of the year, Hurricane Eleven, made landfall in Belize. Timeline Systems Hurricane One The Mobile Hurricane of 1870 The first officially recognized tropical cyclone of 1870 made landfall near Mobile, Alabama, on July 30, though little is known about its genesis or track. According to one report, barometric pressure fell to , but this is considered dubious. The storm's passage was brief, with the strongest winds confined to a period of about two hours in the early afternoon. Storm surge flooding damaged coastal installations along the shores of Mobile Bay, and several steamboats were either sunk or blown ashore. The winds uprooted