Hurricanes form when a precise set of weather conditions are met that cause a wind storm to develop sustained speeds of at least 74 miles per hour. Despite these conditions often being met, it is rare that a storm develops into a hurricane.
Hurricanes use moist, warm air as fuel. This air rises up from over the ocean's surface, leaving less air near the surface. This causes a lower air pressure area to form below.
"New" air with higher air pressure pushes in, then it becomes moist and warm, too. As this air rises and cools, clouds form. The clouds and wind become a system and spin and grow, fueled by heat from the ocean and surface water evaporation.
When the wind speeds in this storm reach 74 miles per hour, the storm is officially considered to be a hurricane.