Here's an interesting one for you. Started my jeep yesterday and the wipers didn't work. Drove back to my house (checking radomly) and checked the fuse which was good. Tried the switch again and they worked fine. Later last night I went to pick up the woman from work, worked fine. Started jeep this morning...do not work.
Only thing I can figure is a bad connection somewhere and in the cold the metal is contracting. Only other thing I can guess is a bunch of snow fell down the cabin air intake, melted and has now frozen the wiper linkage in place, but I wiggled the wiper arms a bit to try to break it up and didn't seem to do anything.
Edit: posting about it makes me feel better about not braving the -21 to actually go out and look at it. I have moved "rent place with heated garage" up on my to do list.