Hypothermia

Creature gains one level of disadvantage on all Acrobatics, Bravery, Focus, Precision, Sleight and Stamina checks for every level of hypothermia it has.
If hypothermia level is 5 creature becomes incapacitated.
If hypothermia level is 8 creature dies.
If a creature spends one hour in a warm environment it loses one level of hypothermia.