The one they are referencing above, it was bitterly cold the weekend before the start of class, my car was unreliable and I remember snow blowing across the road the whole way down on Sunday at the end of break thinking I was probably going to freeze to death if I had car trouble, but I made it. The next morning the bathroom water pipes on our house were frozen. Hadn't learned to let them drip a little. Got up to get ready for class and they canceled it. IIRC they gave us the next day also. I remember it being a big deal, people were like whoa ISU never cancels class.
EDIT: 1/18/1994 (first day of second semester) high temperature in Ames was -9, low was -21. The AC/DC concert was Dec. 4, 1990 in Hilton. It wasn't real cold but the night before Ames got 9 inches of snow.
https://www.extremeweatherwatch.com/cities/ames/year-1994
www.extremeweatherwatch.com