I'm glad I didn't have to fly before and after Christmas. The cold wave blizzard plus 17000 flights cancelled by Southwest Airlines! There's probably a low chance I would have been on Southwest, but I have had flights with them before. From what I have heard, the problems with Southwest started in Denver, where the significant temperature drop caused them to start cancelling or delaying flights, I believe. Then their scheduling problems became so much larger. Also, I would have probably scheduled a Denver to Detroit flight close to that cold wave day(s).