I remember significant problems back in 2004.   We took our son to SW Minnesota to start college in Aug and it froze down there.   Got home and found out I had a few spots froze as well.    I know the corn was light that year and wet, combined very late too.    The problem was pretty widespread that year but I can't remember just how much the rally was.   Definitely a lot a hand wringing and worry everywhere in the north.