Hello fellow northerner KenK!
I currently reside in North Dakota, and I have carried and used a Glock in Alaska as well, so I'll pass on some info based on my experiences with Glocks in those areas.
No special cleaning is needed, and the only concerns with oil/lubricants is that they be rated for extreme cold-weather use. Some fair-weather oils may thicken and lose their effectiveness in extreme cold, so keep that in mind when selecting a lubricant. Lots of folks use synthetic motor oil for lube, as it won't thicken when cold.
If you fall into the snow with a holstered Glock, you'll need to check it to make sure the barrel is clear of snow. Find a safe place, unholster the pistol, and check it closely. If there is any sign of snow inside the pistol, do NOT fire it until it has been warmed-up, dried, cleaned and lubed. Same thing if you fall into liquid water and pistol gets submerged; water will freeze on cold metal parts, and can act as a barrel obstruction if the gun is fired. Warm it up and dry/clean/lube it before firing.
There is one other thing to keep in mind when using any firearm (or small person-portable machine) under extreme cold conditions, and that is potential problems with frost forming, melting, and then re-freezing on or in the mechanism.
If you take the firearm outside, it gets cold. Then you bring it inside into a warm/moist environment, and frost quickly forms on the metal parts. As the gun warms-up, the frost slowly melts and turns into water, and the water may run down into the mechanism. After that happens, if you take the gun back out into the extreme cold, the water can freeze and interfere with proper functioning. There are a couple of different ways to address this problem: prevention/avoidance, and when you can't prevent it, what to do to fix it.
Prevention can be as simple as leaving the gun out in the cold instead of bringing it inside; lock it in a vehicle or outbuilding, and pick it up when you leave. Especially if you are only going to be indoors for an hour or two, this is probably the easiest way to handle it, IF it can be done safely (don't leave an unsecured firearm laying around for any length of time -- period). If the gun was holstered under several layers of clothing, and didn't get very cold due to your body heat, you can probably leave it holstered, and it will be fine.
If you have to take it into a warm area, unload it if possible, and put it close to the heat source (but not TOO close!) in the building/tent, so it will warm-up quickly. Once it has warmed, wipe off any moisture before it can seep down into the mechanism, and if you see evidence that water has already gotten inside, do a quick field-strip and wipe any water off each individual part with a clean dry rag, then reassemble and function-check the firearm. If the wipe-down may have removed all or most of the lubricant, adding a bit of lube and working the action a few times to distribute it throughout the action is a good idea, if you have the means/time/opportunity and a safe place to do so.
The same goes for the magazines and ammo, although you shouldn't lubricate either of these items; just dry them off after they warm-up, and refill the mag.
Last edited by DJ Niner; 01-05-2015 at 22:59..