“In children, the central nervous system is not fully developed. And similarly in adults 65 or older, the central nervous system—although fully developed—starts to deteriorate, which makes your body less able to cope with changes in the body temperature,” Dr. Bangash said. “So, both age groups are at higher risk.

“When these populations experience a heat stroke, they present with more significant neurologic symptoms such as seizures, delirium, hallucinations and difficulty with speech and hearing,” he added.

For those without air conditioning in their homes or people without housing, local cooling centers are an important resource during extreme heat.

Chronic illnesses can increase risk

“Certain chronic illnesses—such as heart or lung diseases—can increase your risk of heat stroke,” Dr. Bangash said. “And that has to do with the effect of those long-term diseases on the central nervous system and the ability of the body to regulate its temperature.