When storms do form in June and July, they usually develop in localized areas rather than across the wide ocean. The primary incubation zones are the Gulf of Mexico, the western Caribbean Sea, and just off the southeast coast of the United States. Because these storms form close to landmasses, they often have limited time over open water to intensify into major hurricanes. However, early-season systems are notorious for tracking slowly and dropping immense amounts of rainfall, which can cause severe inland flooding. August and September: The Peak Months