Although a rare diagnosis in the Emergency Department, hypothermia affects patients in all environments, from urban to mountainous settings. Classic signs of death cannot be interpreted in the hypothermic patient, thus resulting in the mantra, “No one is dead until they’re warm and dead.” This comprehensive review of environmental hypothermia covers the clinical significance and pathophysiology of hypothermia, pearls and pitfalls in the prehospital management of hypothermia (including temperature measurement techniques and advanced cardiac life support deviations), necessary Emergency Department diagnostics, available rewarming modalities including extracorporeal life support, and criteria for termination of resuscitation.