Mine are up on concrete blocks stacked two high plus an open frame stand, so about 18 inches off the ground. The reason isn't for snow, though, as we almost never get more than an inch or two for a day or two, but so I don't have to bend over as much to work them and so mites falling through the screens cannot climb back up.
Seems like the answer depends on whether you have primarily snow that stays or snow that melts & refreezes. If it falls and piles up, as with Finski, or Canadian beeks, then it's great insulation and the bees can't exit much anyway due to cold. If it melts off, then the ground will be very wet after each snow, and you may want to raise them off the ground to avoid excess moisture problems.