With a category 5 hurricane, you can expect one of these alliterative consequences 18 feet above normal tide
Highest surge will likely occur from extreme northeast Florida ... that Matthew will 
still generate a storm surge of 10 to 15 feet (3 to 5 m) in the ... Keep in mind, these 
are water levels above the ground, and storm ... near normal astronomical tides, 
but expect the water to rise rapidly ... August (1) ... October (18).