Climate change is anticipated to continue to adversely affect public health, with heat stress the predominant threat. Accordingly, heat-related illness is predicted to increase as extremely hot days become more frequent. Heat stroke, the most serious heat-related illness, is a medical emergency that may be fatal if it is not promptly recognized, addressed with early and rapid cooling, and accompanied by multidisciplinary supportive care as clinically indicated. Heat stroke is a preventable illness that occurs in 2 distinct forms-classic and exertional-that have distinct demographic profiles and clinical courses but similar management paradigms.