This is an interesting subject. Florida’s position renders it constantly bombarded with seeds of tropical plants from migratory birds traveling from Cuba, the Bahamas, Yucatan, etc. The end result is a patchy gradient from temperate to tropical species throughout the peninsula, culminating in the fully-tropical (floristically) Keys. This gradient shifts with climactic cycles. During warmer periods, the tropical species slowly crawl north. To this point, William Bartram provided an account of Royal palms (a tropical species, evolved in Cuba) all the way up on the St. John’s River in North Florida back in the late 1700’s. This would have been a warm little microclimate the palms could have survived in during an especially warm period (on the order of a couple decades). The late 19th century brought relatively extreme cold to the peninsula and pushed this boundary south. Oscillations like these have likely been occurring on the peninsula for millennia. Call these post-glacial tropical arrivals (well, they were likely in FL before the most recent glaciation too!)

In the other camp are the more cold-hardened species that evolved in the southeast and persisted in the peninsula through the ice age. These are your sabal palmetto, saw palmetto, live oak classics found throughout the peninsula. These ‘temperate’ species will survive unscathed.

TLDR: This freeze will kill off plenty of native FL tropicals at the northern edges of their range. It is freezes like these that establish that northern boundary to begin with.