Originally published on NIH:
As we age, our ability to adequately respond to summer heat can become a serious problem. Older people are at significant increased risk of heat-related illnesses, known collectively as hyperthermia, during the summer months. Hyperthermia can include heat stroke, heat edema (swelling in your ankles and feet when you get hot), heat syncope (sudden dizziness after exercising in the heat), heat cramps, and heat exhaustion.
Experts at the National Institute on Aging, part of the National Institutes of Health, say knowing which health-related factors may increase risk could save a life.