Yeah snow is rare in DC in November/December. There was a huge snowstorm in the DC area in November 1987. Not too many more since.
I graduated from OCS in Quantico in 1989 and was the last plane out of what is now Reagan National due to a snowstorm that hit the east coast. Flight connected in Atlanta and had to layover due to Atlanta International closing during the same storm.
There was also a rather large snowstorm that November that our Company Commander allowed us to have a snowball fight in just prior to Company PT.