Exertional heat stroke is most likely to occur in which conditions and what core temperature?

• A. Hot and humid weather; CNS dysfunction; Temperature > 105
• B. Cold weather; normal cognition; Temperature < 98
• C. Dry desert; no CNS symptoms; Temperature 100
• D. Mild heat; no fever; Temperature 98-99

Answer: (A)

Exertional heat stroke happens when intense physical activity in hot, humid conditions overwhelms the body's ability to cool itself, leading to a dangerous rise in brain temperature and CNS dysfunction. The defining feature is a core temperature well above 105°F (about 40.6°C). Humidity makes evaporative cooling less effective, so during strenuous work heat accumulates quickly. The accompanying CNS dysfunction—confusion, agitation, seizures, or unconsciousness—shows the brain is being affected, which is the key marker separating heat stroke from milder heat-related illnesses. Other scenarios don’t fit because they lack either the dangerous combination of hot, humid conditions with how hard the body is working, or the presence of CNS symptoms and the very high core temperature required for heat stroke.