The creature has a blood temperature that coincides with the temperature of its surroundings. Such a creature will be much more active in a warm environment and will become sluggish as it gets colder. If it is cool in the environment, the creature receives a -1 penalty to all physical actions. If it is cold, the creature gets a -2. If it is at or around freezing, the creature receives a -3 penalty, and at sub-zero temperatures the creature receives a -4 penalty.