A couple of things you could try with you cannister stove starting with the easist:

1) Put the cannister in your pocket or next to your body initially to warm it up.

2) Use a small insulated pad under the stove in milder winter weather to keep it off the snow. I've heard of people sewing a kozy for their stove.

3) Use a charcoal handwarmer(s) under the stove or rubber band it to the side. You probably have handwarmers in your kit in the first place!

4) Put the cannister in a pan of water to warm it up. Even water right at 0*C will be warmer than the outside air and it will counteract the lowering of the cannister temperature as the gas is consumed and the internal pressure drops.

5) Use a wrap-a-round windscreen. They always say, "don't do this because it will overheat your cannister and it will go boom." Nonsense, when its -30*C with a little breeze, that worry is gone. The heat from the flame will reheat the cannister and help evaporate the gas. You can judge for youself by touching the top of the cannister, if you can hold you hand on it you are fine. If too warm then open up the screen a bit more. Just don't wrap it tight to the stove and you will be fine. If you are still not convinced, then add a circular bit of tinfoil under the burner as another shield to moderate the heat on the cannister.

I've got a Coleman X-treme from the '90s. I can't find fuel for it anymore but luckily I anticipated this and have a stock of about 12 cannisters. It works pretty well in moderate cold, but I've never used it at -30*C. (When a local outdoors store renovated they threw out a whole box of these things, I told them I would take it off their hands... but alas I just missed out on it.)