Here is the map of the devastation caused by Harvey, superimposed on Florida:
Irma is already a Cat 5 storm, bigger than Harvey. And it could become the first Cat 6 storm in history.
Get out. Now. Right now. Don’t wait for the roads to jam. Flee north and inland right this minute. Don’t wait until the rest of the population of Florida is caught in the trap and panics. Get out right now. This is going to be really, really bad.