Heatwave Alert: Millions in the U. S. Face Dangerous Conditions

The U. S. is bracing for a severe heatwave this weekend, with a significant portion of the Eastern region under threat. By Sunday, a staggering 38 million people will be at "major" risk of heat stress, while another 7 million could face "extreme" danger, according to the National Weather Service. The Midwest and Central Plains are expected to experience the highest temperature anomalies, with mercury levels soaring to the mid-to-upper 90s Fahrenheit (mid-to-upper 30s Celsius). The combination of scorching heat and high humidity will lead to perilous wet-bulb temperatures, pushing the human body's cooling mechanisms to their limits. Heat advisories have been issued in parts of 15 states, stretching from Nebraska to Florida, starting Friday. These warnings are expected to remain in effect through Monday. Northern Illinois is predicted to be one of the hardest-hit areas on Sunday, with extreme risk also extending to central Iowa, Missouri, northwestern Tennessee, and parts of west-central Florida. By Monday, the extreme risk could spread to central Tennessee, western Kentucky, and southwestern Indiana. The National Weather Service advises people to stay hydrated, seek air-conditioned spaces, avoid direct sunlight, and check on vulnerable neighbors and relatives. Wet-bulb temperature is a crucial metric that combines heat and humidity to assess heat stress. High humidity hampers the body's ability to cool itself through sweat evaporation, increasing the risk of heat-related illnesses, especially for children, the elderly, and those with chronic health conditions. Meteorologists use the wet-bulb globe temperature (WBGT) for a more comprehensive measure of heat stress, factoring in air temperature, wind speed, cloud cover, and solar radiation. Over the weekend, WBGT values are expected to reach the upper 80s and low 90s Fahrenheit (low 30s Celsius) across the Midwest and Southeast. Values exceeding 90 degrees Fahrenheit (32 degrees Celsius) can cause heat stress in just 15 minutes of outdoor activity. This isn't the first time the Eastern U. S. has faced such extreme conditions this summer. In late July, a heat dome led to warnings for nearly 170 million Americans as WBGT values skyrocketed. With global warming on the rise, these extreme wet-bulb conditions are becoming more intense and prolonged, highlighting the importance of WBGT in assessing human survivability in a changing climate.