I see that the map is based on data through 2005. My zone 9b place in Highlands County, Florida has had quite a few nights down to about 20 degrees in the last 3-4 winters.
I've heard that even modest overall climate change can cause extremes of temperature, etc. in some areas.
Still, I'm hoping that this is just a short-term trend. Someday I'd like to eat a loquat.