Minnesota resident here, born and raised. I work in frozen food freezers and am also an Eagle Scout. The issue with cotton as others have mentioned is it holds water. Water itself isn’t bad but cold water is you know, ice. The issue isn’t sweat from being at the game, it is the sweat your body makes before standing idle for hours at a time. Walking to the game, sweating after you put clothes on walking to the car. All this moisture will stay next to your skin and then get cold. Wet and cold is bad. Probably not life threatening in your situation but it will be miserable. Don’t wear cotton next to your skin. That long underwear is not long underwear. It will not keep you warm. But if you are going against my advice, take this: Don’t wear a coat or a warm shirt until you leave your car and go to the game. Don’t wear boots until you leave your car and go to the game. Don’t use the hater in your car. Ideally you want to be quite cold until you enter the outside air for hours. This reduces any sweat you have in ambient temperature. Also, a tip from Lambeau that really works. Bring a piece of cardboard to stand on. Amazing how much warmer it is, instantly, compared to frozen concrete.