High Quality Content by WIKIPEDIA articles! The 2004 Atlantic hurricane season officially began on June 1, 2004, and lasted until November 30, 2004. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. The 2004 season exceeded these conventional limits slightly, as Tropical Storm Otto formed on the day before the last day of the season and lasted three days into December. Ironically, although a weak El Nino was emerging during the summer, the season was well above average in activity, with fifteen named storms and one of the highest Accumulated Cyclone Energy totals ever observed.