Sabal minor MSI
From Palmpedia - Palm Grower's Guide
This palm, or some forms of this palm, seem to be able to withstand temps in the teens with little damage. Palms burned badly often come back, even with near total defoliation, so it has to be listed as one of the most cold hardy palms. This palm is highly tolerant of humidity as well, so it is one of the more adaptable palm species.