 The 1858 Atlantic hurricane season was one of only three Atlantic hurricane seasons on record in which every tropical cyclone intensified into a hurricane ( the others were in 1852 and 1884 ) . The first hurricane was first observed over the northwestern Caribbean Sea on June 12 . The sixth and final storm was last noted on October 26 . These dates fall within the period with the most tropical cyclone activity in the Atlantic . Three tropical cyclones during the season existed simultaneously . Two of the cyclones have only a single known point in its track due to a sparsity of data . Operationally , another tropical cyclone was believed to have existed over the eastern Atlantic between September 17 and September 18 , but HURDAT – the official Atlantic hurricane database – excludes this system . However , in the absence of modern satellite and other remote @-@ sensing technologies , only cyclones 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 four tropical cyclones per year between 1886 and 1910 has been estimated . Of the six known 1858 Atlantic cyclones , five were first documented in 1995 by Jose Fernandez @-@ Partagas and Henry Diaz . 
