Fabricate a cover for the lock...plastic bag will work...could build a
more elaborate cover out of wood metal etc....depends on your free
time....other things

We got one at work that freezes on our gate...I am usually the earliest
to work and I have a propane torch I keep just for that purpose...to
heat it up.

Ive tried the plastic bag thing at work but people who leave later than
I do wont put it on.....*******s.....so I torch that lock when its
frozen....Ive also been known to take a large ball pein hammer to it
also.....I just lay the lock on my bosses desk and tell him to get
another....of course we dont use master locks....at least I dont think
its a master lock as it is brass and a 4 number combination...