Why do hurricanes form in some places but not others?

Hurricanes will only form where the sea surface temperature is 27 degrees C or above. This area of the ocean is located between the Tropics of Cancer and Capricorn, otherwise known as the ITCZ. The sea surface has to be this particular temperature because a key stage of the formation of a hurricane is where the warm (27 degrees or above) ocean beneath a storm evaporates, providing the storm with energy and therefore fuelling a hurrincane. If the ocean is any colder than 27 degrees then this water is not able to evaporate.

This means hurricanes will only form where the sea is warm enough.