40 below is common. But generally the problem at altitude is protection from the cold. The best way to keep warm is to layer up. The layering principle traps air, and still air insulates. The middle layers insulate - for 8000m peaks, I use a combination of Polartec and down garments.
Skin is waterproof and breathable, it regenerates and lasts forever.
It does go wrinkly with time, soft and wrinkly if wet for too long, and it's easily rubbed off and burns in the sun. This layer can be worn in the bath, on the beach or in the office. The temperature reading's interesting because it has to be hung in the tent to get an air temperature - on the wrist it gives wrist temperature. Avocet Vertech - takes over as an altimeter when above 6,000m and up to 10,000m. Around my neck is a Buddhist Puja necklace, a piece of cord with a knot blessed by a lama or monk - mine has an extra tassle, allegedly blessed by the Dalai Lama, and I must get round to taking it off as I'm neither superstitious nor Buddhist.