[AN: Having never been anywhere near Wisconsin, I'm guessing this is one of those four-seasons-in-one-day places. Like Melbourne]
I also live in Wisconsin, heh, and yes. It's NOT unusual, especially in spring, to have a hard, cold, frost, even snow, at night, and by morning be foggy, and by midday actually being warm enough you need to wear lightweight clothing, even possibly start sweating, while working outdoors, only for it to get cold again at night. That's why spring is such a stormy season. Fall's almost as bad.