Hot weather causes an average of 702 deaths nationwide each year, according to a new report released by the Centers for Disease Control and Prevention, based on data from 2004 through 2018. Most of the deaths (90 percent) occurred from May to September, and about 70 percent of the victims were men. More than a third of those who died (37 percent) lived in Texas, Arizona and California. Direct exposure to the heat accounted for about 60 percent of the deaths in this 15-year span, but for the remaining 40 percent, heat was considered a contributing factor, having exacerbated an existing condition, such as heart disease, hypertension or respiratory disease. Hyperthermia, the medical term for heat-related illness, develops when the body cannot cool itself sufficiently through sweating. Symptoms may include a fast but weak pulse, muscle cramps, nausea and dizziness. Referred to as heat exhaustion, this condition, if not resolved, can progress to heat stroke, with the body temperature rising to 103 degrees Fahrenheit or higher and the skin becoming hot and dry, with little to no sweating. A heat stroke is considered a medical emergency (dial 911) because a very high body temperature can cause brain or other organ damage and can be deadly. The very young and the very old are considered most vulnerable to hyperthermia, but hot weather can shift from uncomfortable to dangerous for people of any age who stay out in the heat too long or engage in strenuous activity. Drinking alcohol increases the risk for heat stress, as does taking medications that inhibit perspiration or limit the body’s ability to regulate its temperature, including beta-blockers, diuretics and calcium-channel blockers.