A humid heatwave is expected to affect much of North America in the coming days and our bodies aren’t well designed to deal with it.
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A 90F day in New York can feel more tiring than a 100F day in Arizona, and the reason lies in the moisture content of the air, not just the temperature.
While Europe grapples with a record-breaking heatwave that has resulted in numerous fatalities, North America is preparing for a “heat dome.” This phenomenon will not only bring extremely high temperatures but also humidity that will make the heat intolerable.
Weather forecasts now often include “feels like” temperatures in addition to air temperatures, recognizing that humidity significantly impacts how heat is perceived and managed by the human body.
Humans are adept at maintaining a body temperature of around 98.6F (37°C) through sweating, even while exercising or on very hot days. Sweat itself does not cool the body; rather, the evaporation of sweat from the skin dissipates heat into the air.
In dry conditions, sweat evaporates quickly, allowing body temperature regulation even on hot days. However, in humid environments, the air is saturated with moisture, hindering sweat evaporation and causing individuals to perspire profusely as the body struggles to release excess heat.
This situation can quickly escalate from discomfort to danger as the body’s temperature rises. The body tries to cool down by redirecting blood to the skin and increasing heart rate, which strains the heart. Rapid dehydration can occur as sweating continues without relief. If body temperature continues to rise, heat exhaustion or heat stroke may develop, with the latter posing a life-threatening risk if not promptly treated.
As fans gather to watch the World Cup across North America, places like Toronto, where Portugal and Ronaldo will be playing on Thursday 2nd July will be facing humid temperatures exceeding 100F. (Photo by Molly Darlington/Getty Images)
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Heat stroke is the most severe form of heat-related illness and is considered a medical emergency. It arises when the body’s cooling mechanisms are overwhelmed and cannot maintain normal temperature. According to the CDC, symptoms of heat stroke include confusion, slurred speech, loss of consciousness, seizures, a very high body temperature, and skin that may be either hot and dry or heavily sweating.
Without immediate intervention, heat stroke can cause lasting damage to the brain, heart, kidneys, and other organs, and can be fatal. Individuals displaying these symptoms should be moved to a cooler environment promptly while emergency medical help is summoned, as rapid cooling can be life-saving.
