I’ve lived in the South my whole life (not in the mountains), and average daytime temperatures in November and December can range from the 40s to the 60s, so snow in December is rare unless you do live at a higher elevation. The coldest part of winter here falls in January or February.
I’ve lived most of my life in Oregon, Cali. and Maryland. I’ve also seen Christmases in Japan and the U.K. I’ve only ever seen one white Christmas, in Maryland.