Newbie Mummy Bug Question

Learn to keep the bag adjusted so your nose and mouth are directed out of the hood. I once had your problem and realized that I'd have to change my ways when I awoke, after a night of temperatures in the teens, and found the zipper encased in a lump of ice, from my condensed breath. I had to chew the ice off the zipper before I could get out of the bag. My water bottle was frozen solid and my boots were so frozen I couldn't get my feet into them.

When it is so cold, condensation on your bag is more or less a given. I have the same MB bag, except it is the #2 and have slept in it a few times with temps in the 10 degree range. Pull the draft collar tight, and adjust the hood and bag closer so your breath is going straight to the outside of the bag, best you can arrange. You move around when sleeping anyway, just do your best. I have woken up to an ice layer on the outside of my bag by the breath hole everytime its' that cold. Pick off the ice, get up, get moving. The bag inside was not really wet under the ice. Damp I am sure, but not wet. Try not to breath in your bag. That is not a good plan.