Here is the full list of all 16 Warmth achievements.
The base game contains 14 achievements, and there is 1 DLC pack containing 2 achievements.
You've placed your first torch!
You've placed your first campfire!
You've warmed up your first dog!
You've warmed up your first boy!
You've warmed up your first grandma!
You've warmed up your first snowman...
You've finished levels 1 to 8.
You've finished levels 9 to 16.
You've finished levels 17 to 24.
You've finished levels 25 to 32.
You've finished levels 33 to 40.
You've finished levels 41 to 48.
You've finished levels 49 to 56.
You've finished levels 57 to 64.
You've finished levels 65 to 72.
You've finished levels 73 to 80.