About 99 percent of hurricanes occur during hurricane season, which runs from June 1 to November 30 in the Atlantic Ocean and May 15 to November 30 in the Pacific Ocean. In the Atlantic and Pacific, September is the month with the most hurricanes. During an average season, three hurricane-strength storms occur in September. Many hurricanes also form in August and October, but strong hurricanes seldom occur in November.
From 1851 to 2013, major hurricanes hit the U.S. coastline 46 times in September, 26 times in August, 17 times in October, five times in July and twice in June. Texas was the only area to break pattern, experiencing 10 strong storms in August but only nine in September. The same data set from the National Oceanic and Atmospheric Administration recorded September 10 as the day with the highest number of hurricanes making landfall on the U.S. coast.
During September, the warming ocean waters and the lower wind shear help create stronger storms capable of hurricane-strength wind. As the hurricane season comes to an end, lower water temperature and increased wind shear hinder the development of hurricane-strength storms. Since 1870, only 32 hurricanes have been recorded between December and May, outside of hurricane season.