Now it is the Florida coast that is in danger because of the Sharknates, the sharks being carried by tornadoes to any part of the United States. All the people of Florida are in danger, although it seems that on this occasion they are alerted.
Fin is in Florida with his kids spending the holidays there, since Florida is a site chosen by millions of Americans to spend their vacation days. As soon as he learns what is going to happen, he sets to work to put his children safe.
The Sharknados are approaching south, to the coast of Florida and in doing so they are fusing. With the merger they become even bigger, which makes them more deadly and dangerous than ever. When they reach the coast, they will devastate her completely, killing everyone in their path, including Fin and her children.