was the ninth named storm, the sixth hurricane, and the fourth major hurricane of the 2004 Atlantic hurricane season. It formed on September 2 as a tropical depression, became a tropical storm on September 3, and a hurricane on September 5. It was a Cape Verde-type hurricane that reached Category 5 strength on the Saffir-Simpson Hurricane Scale, the highest possible category. Ivan also gained unprecedented intensity at low latitudes—Category 4 at only 10.6° N—after having existed for only a few days. Its minimum recorded pressure of 910 mb made it the sixth most intense Atlantic hurricane on record. It caused an estimated $13 billion dollars worth of damage in the United States, making it the third costliest hurricane to ever strike the U.S.
Ivan struck Grenada directly on mid-day September 7 at Category 3 intensity, causing at least 39 deaths and damage to over 85% of the structures on the island. It continued across the Caribbean Sea, reaching Category 5 intensity before passing close to the Jamaican coast and Grand Cayman and crossing the western tip of Cuba. Twenty deaths were reported in Jamaica, and damage to over 80% of the buildings was reported on Grand Cayman.
Ivan then moved into the eastern Gulf of Mexico and weakened to a strong Category 3 storm. It continued on a track towards the north-northwest, making landfall in the U.S. near Gulf Shores, Alabama. After landfall, Ivan dropped heavy rains on the Southeastern United States, turned east, and then later looped south and through Florida and regenerated into a tropical storm for a short time in the Gulf of Mexico. The new tropical system moved into Louisiana and Texas, causing minimal damage.
Ivan broke several hydrological records; it is credited with possibly causing the largest ocean wave ever recorded, a 91 foot (27 meter) wave that may have been as high as 131 feet (40 m), and the fastest seafloor current, at 2.25 meters per second (5 miles per hour).
The name "Ivan" was retired in the Spring of 2005 by the World Meteorological Organization. It will be replaced in 2010 by "Igor".