Actually I did have it happen to me in Northern Minnesota. We were in the coach and headed right into a rolling thunderstorm. I think the outside air temps dropped >25 degrees immediately and the inside of the windshield fogged over within a couple of seconds.
I was new to driving the coach and had to do some quick thinking to find the switch for my large defroster fans and get the beast slowed to a safe speed until my windows cleared.
Scary stuff when you're on the business end of the steering wheel.