It’s because an area of the tropics that lies between five degrees north and five degrees south latitude of the equator has ocean waters of at least 80°F over a large area. This is the first ingredient needed for a hurricane to develop. The second ingredient is wind blowing westward off the continent of Africa.
Hurricanes feed on warm moist air rising from the Atlantic Ocean. Warm water evaporates (turns into water vapor) from the surface of the ocean and rises. As it rises, it cools. This causes the water vapor to condense (to become more dense or compact), forming cumulonimbus clouds. A cumulonimbus is a very large thunderstorm cloud that extends to a great height. Once these clouds form, the first stage of hurricane development has begun.