For a hurricane to form, a few different factors have to come together. A hurricane requires open ocean with a sea-surface temperature above 72 degrees Fahrenheit. The warm surface waters must extend to a depth of about 200 feet. This allows the hurricane to gain water for the storm. There must be an area of disturbed weather over the ocean, such as a thunderstorm, from which the hurricane can form. The hurricane also needs weak vertical wind shear. Wind shear is the change in wind with height. If you have strong wind shear then the winds may be moving very rapidly high in the storm but slowly in the bottom of the storm. On the other hand, if you have weak wind shear, then the winds are moving at about the same speed througout the entire storm. When you have weak wind shear, the storm can maintain its strength and become a full hurricane.