The 1858 Atlantic hurricane season was one of only three Atlantic hurricane seasons where every tropical cyclone intensified into a hurricane, after and before the 1852 and 1884 seasons respectively. 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. The season also had an accumulated cyclone energy (ACE) rating of 44.79. 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, however the Atlantic hurricane database excludes this system. Although, with the absence of modern satellite and other remote-sensing technologies, the actual total was likely higher. An undercount bias of zero to six tropical cyclones per year between 1851 and 1885 has been estimated. Of the six known 1858 Atlantic cyclones, five were first documented in 1995 by Jose Fernandez-Partagas and Henry Diaz. 6 storms, 6 hurricanes, 0 major hurricanes (Category 3+). Strongest: an unnamed storm (105 mph). Accumulated cyclone energy ≈ 45. Wiki link