Lots of good preventative tips listed so far.
If you come out to your lock being frozen and you aren't able to use WD-40 or lube then and there to get it unfrozen, try breathing on it for a minute or two. If you are up close your warm breath should melt whatever little moisture is in there freezing the mechanism shut. You are however putting more moisture in there that will freeze again, but at least you'll be unlocked and on your way to where you can use some WD-40.
Breathing on it beats peeing on it for sure.
great thread and tips.
another solution is this (if you arrive to a frozen lock with no WD-40, lube, etc.)
heat the key up (use a match or lighter - but be careful around the plastic portion of the key)
and then immed. insert it into the lock. it may melt the ice / unfreeze it enough to get home and lube it.
Another easy option if you don't have a lighter.
Hand sanitizer can be used to open a frozen lock. Just coat the key in it and then insert.
You might give a product called T-9 from Boeshield. It is a silicone lubricant developed for aerospace and marine use. We use it in tampa on boat stuff...electronics, etc. BTW...WD40 acts more like a degreaser than a lubricant. T-9 is available in small aerosol cans as well.
My door's lock freezes a lot and I carry a mini lock de-icer in my bag. The regular size de-icer is the size of can of Pledge, so not really handy to lug around. You can get both at the hardware store. The mini one has a nozzle on the end that squirts a gel-like alcohol into the keyhole to melt the ice. Good tip with the hand sanitizer, it probably has the same kind of alcohol. Straight rubbing alcohol would work, too.
Would graphite lube work, after getting home and warm/dry ?
Used to use it in the military for a bunch of things.
Also, some CLP. If it works for all of our weapons through most weather, might work for the lock.
I have now switched to FrogLube or Militec-1. (For my home defense system.)
That anti-seize stuff works well. You can buy it at any auto parts store. It comes in a little round can like, about size of a small bottle of chain lube. A lighter on the key will do as well.