High Quality Content by WIKIPEDIA articles! The 1867 Atlantic hurricane season was the period in 1867 during which several tropical cyclones developed in Atlantic basin. 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. These dates closely delimit the modern-day hurricane season in the Atlantic. 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.