How can I prepare my home to be vacant for a month?
I don't have an exhaustive answer, but off the top of my head, I would say don't turn off the heat entirely.  You don't want frozen pipes, and refrigerators can be damaged if they are left running in freezing temps.  If it were me, I'd probably leave the thermostat at about 10 C.  I would also turn off the water entirely so that even if a pipe bursts, you don't end up ruining anything.  Also, not sure what crime is like there, but may want to figure out how to make it look like the place is occupied.  Snow accumulation could make that tricky (i.e. no tracks means no people).