Speaking from experience a properly clad soldier can function without hindrance for about half an hour in -40<sup>o</sup>before physical faculties deteriorate. After that it deteriorates rather slowly, but exponentially the body will have a harder and harder time to keep its body temperature up. A MechWarrior emerging from an active mech I suspect however, doesn't have the luxury of proper arctic gear, in which case the deterioration starts within the first minute of exposure. Sure, one could argue that they can keep a coat in the cockpit, but the gear needed for actual actions in such conditions are rather extensive and hard to slip into in the cockpit of most 'Mechs.<br/><br/>Although that's reality.