The 1867 Atlantic hurricane season lasted from mid-summer to late-fall. A total of nine known tropical systems developed during the season, with the earliest forming on June 21, and the last dissipating on October 31. On two occasions during the season, two tropical cyclones simultaneously existed with one another; the first time on August 2, and the second on October 9. Records show that 1867 featured two tropical storms, six hurricanes and one major hurricane (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