Hurricanes are tropical storms. The warm humid air of the tropics rises. As the air rises, it cools, and the moisture condenses to cloud and rain drops. Heat energy is released in the condensation process. Tropical storms usually occur in late summer and fall when the oceans in the northern hemisphere are at their warmest. When a hurricane makes landfall it loses the tropical moisture, which is the fuel that feeds the storm. Hurricanes weaken rapidly over land, due to the quick loss of water.