Battery ....RIP,......... Death By Polar Vortex??

I have had excellent luck with Interstate. They were the only engine start batteries that would survive the vibration in my tool truck. I have gotten 7 years out of one in the wife's car. Having starting problems yesterday though. The battery was almost dead. Too many short trips in -50° wind chill.
The weather warmed up into the 30's today. I need to pop the back seat up in the Buick and test the battery. It still isn't happy.