For the folks that have forgotten or just don't know, early to mid March can still get very cold deep down into the US. For example, on 3/2/1980 there was snow falling in much of the SE with temperatures as cold as the teens during the daytime! On 3/13/1993, the Storm of the Century caused heavy snow and blizzard conditions for many followed by lows down into the teens and even the single digits in some places like Birmingham. These kinds of temperatures would challenge the coldest all of this winter.
March, 1960, was the coldest month of the entire winter for much of the SE with 10 degrees for the coldest at Atlanta! It was colder than an average January there! There wasn't just one nor just two but THREE major winter storms there during the 1st half of March!!! They don't get major winter storms but about once every 2 winters on average.
Two more examples: March of 1932 and March of 1890 were each colder than Dec, Jan, or Feb at Atlanta and probably much of the SE. Those were two of the three warmest winters on record in much of the SE.
Don't count your winter chickens before the March lion has his say!