It wasn't the coldest night but the most uncomfortable I was at a game was at Brebeuf last year. It was 60 degrees or so late in the afternoon and dropped to around 40 degrees and no one was dressed for the dramatic temperature drop. Not only was it getting colder, but a steady rain turned into a downpour. Cathedral won the game 21-7, which was the only good thing about that night.
I also remember a night in the playoffs at Bloomington High in 1973. We passed around a flask and it was still miserably cold that night. It was the night Cathedral broke Bloomington's 60 game winning streak, so it was well worth it though.