11 named storms, seven of which to intensify into a hurricane, and three would strengthen further into a major hurricane. Seasonal summary The Atlantic hurricane season officially began on June 1, but activity in 1990 began five days earlier with the formation of Tropical Depression One on May 25. It was an above average season in which 16 tropical depressions formed. Fourteen depressions attained tropical storm status, and eight of these attained hurricane status. There was only one tropical cyclone to reach major hurricane status (Category 3 or higher on the Saffir–Simpson Hurricane Scale), which was slightly below the 1950–2005 average of two per season. Unusually, the season featured no landfalling tropical storms in the United States. This was only the sixth such occurrence known, the other seasons being 1853, 1862, 1864, 1922, and 1962. Overall, the storms of the season collectively caused 171 deaths and approximately $153 million in damage. The last storm of the season, Hurricane Nana, dissipated on October 21, over a month before the official end of the season on November 30. The activity in the first two months of the season were limited in tropical cyclogenesis, with the second tropical depression of the season not developing until July 22. Following that, the season was very active, and there was a quick succession of tropical cyclone development from late-July to mid-August. The Atlantic briefly remained dormant, and activity resumed on August 24 with the development of Tropical Depression Eight (Hurricane Gustav). Although August was a very active month, there were only two named storms in September, both of which became hurricanes. Activity in October was higher than average, with five tropical cyclones either forming or existing in that month. Following an active October, no tropical cyclogenesis occurred in November. The season's activity was reflected with an accumulated cyclone energy (ACE) rating of 97, which is slightly above the mean value of 96. ACE is, broadly speaking, a measure of the power of the hurricane multiplied by the length of time it existed, so storms that last a long time, as well as particularly strong hurricanes, have high ACEs. It is only calculated for full advisories on tropical systems at or exceeding 39 mph (63 km/h), which is the threshold for tropical storm strength. Systems Tropical Depression One Tropical Depression One formed on May 25 from a weak low pressure area to the west of Jamaica, which