A "heat dome" spanning large regions brought dangerously high temperatures to millions of people over the recent holiday weekend, prompting medical professionals to share guidance on staying safe amid extreme heat conditions.

Emergency room physicians emphasize the importance of maintaining proper hydration. Dr. Reed Caldwell, chief of service at the Ronald O. Perelman Center for Emergency Services at NYU Langone’s Tisch Hospital, advises that waiting to feel thirsty can mean the body is already behind on fluids. He recommends drinking water regularly, even if one does not feel thirsty. Dr. Bradley Uren, clinical associate professor of emergency medicine at Michigan Medicine, adds that for most people, plain water is sufficient for hydration, and specialty drinks with electrolytes are generally unnecessary. Incorporating fresh fruits and vegetables into the diet can also support hydration. A practical indicator of insufficient fluid intake is dark yellow urine.

To minimize heat exposure, experts suggest scheduling outdoor activities outside of the hottest periods, typically late morning through late afternoon. Wearing light-colored, natural fabrics such as cotton and linen is preferable to dark or synthetic materials, according to Dr. Caldwell. Spending as much time as possible in air-conditioned environments is advised. For those without air conditioning at home, recommended measures include shading windows with blankets or sheets during the day, keeping windows open at night, and using fans to improve air circulation. Lightly applying cool or room-temperature water to the skin can help reduce body temperature.

Recognizing early symptoms of heat-related illness is critical. Dr. Christopher Bazzoli, an emergency medicine physician at the Cleveland Clinic, notes that heat edema—swelling in the ankles, hands, and feet—can be among the first signs of heat exposure and should prompt relocation to a cooler place. Heat exhaustion, a moderate heat illness, can manifest through nausea, dizziness, muscle cramps, and a rapid heartbeat. Individuals experiencing these symptoms should rest in a cool location and increase fluid intake; a cold shower may assist in lowering body temperature.

Heat stroke represents a more severe and potentially fatal condition. It is characterized by a body temperature of 103 degrees Fahrenheit or higher, hot and flushed skin that may be dry or moist, confusion, uncoordination, and shallow, rapid breathing. Immediate emergency assistance by calling 911 is essential if someone displays these signs.

Certain populations face higher risks of heat-related illness, including older adults, infants, pregnant women, and individuals with preexisting conditions such as heart disease, lung or kidney disorders, and diabetes. Careful monitoring of these vulnerable groups during extreme heat is especially important.