In many cases, evacuations may start 72 hours before a hurricane's landfall. Evacuation must start early in some areas because of the amount of time necessary to evacuate people in those areas. An area with more people will take more time to evacuate than one with fewer people. A Hurricane Watch is issued when hurricane conditions are a good possibility within the upcoming 36 hours. A Hurricane Warning is issued when hurricane conditions are expected within the next 24 hours.
Hurricanes are hard to predict.
It is impossible to know a definite storm track, so very often watches and warnings are issued for a large portion of Florida's coastline.