Heat dome impacts 70 million Americans; experts stress rapid cooling for heat-stroke victims

A persistent high-pressure system, described by meteorologists as a heat dome, is affecting an estimated 70 million people from New Mexico to North Carolina. Daytime temperatures are reaching the 100 °F range, with heat-index values higher due to humidity.

AccuWeather meteorologist René Duff explained that the dome creates sinking air that compresses and warms, while also drying the atmosphere. She noted that the core of the heat is expected to shift westward later in the week, bringing record-level temperatures of around 115 °F to Phoenix and moving much of the 90-degree heat into California and the Four Corners region.

National Weather Service meteorologist Marc Chenard said extreme-heat advisories remain in place for Arkansas, Tennessee and parts of the Gulf Coast, and highlighted the unusual intensity of the current heat waves, which he linked to the influence of El Niño.

Health experts warned that individuals with heart disease, high blood pressure or higher body-mass index are at greater risk of heat-related illness. Douglas Casa, CEO of the Korey Stringer Institute, said that nighttime temperatures are rising faster than daytime highs, preventing the body from recovering after daytime exposure.

Casa outlined basic preventive measures: staying out of direct sun, drinking water or electrolyte fluids, wearing light, loose clothing and taking frequent breaks. He emphasized that rapid cooling is critical for heat-stroke victims, recommending immersion in cold water before transport. "Cool first, transport second," he said, noting that a core body temperature of 108 °F must be lowered below 104 °F within about 30 minutes to improve survival odds and reduce the risk of long-term organ damage.