Hurricanes evolve through a life cycle of stages from birth to death. A tropical disturbance in time can grow to a more intense stage by attaining a specified sustained wind speed. The progression of tropical disturbances can be seen in the three images below.
Hurricanes can often live for a long period of time -- as much as two to three weeks. They may initiate as a cluster of thunderstorms over the tropical ocean waters. Once a disturbance has become a tropical depression, the amount of time it takes to achieve the next stage, tropical storm, can take as little as half a day to as much as a couple of days. It may not happen at all. The same may occur for the amount of time a tropical storm needs to intensify into a hurricane. Atmospheric and oceanic conditions play major roles in determining these events.
Below, in this satellite image from 1995, we can see different tropical disturbances in each stage are evident. At the far left, Tropical storm Jerry is over Florida, while Hurricanes Iris and Humberto are further east, amongst a couple of tropical depressions.
Image by: GOES Project