How to drink in a cold environment?
Toady mentions his "hackneyed" solution to this in the dev blog and then in the release notes, but it's not obvious.
- ability to make campfire (from 'g') and warm items at campfire/fire/magma (from 'I') in adv mode
What you have to do is make a campfire and then warm your water skin at it until it turns to liquid, and then you can drink from it.