WASHINGTON — Public health officials across the United States intensified heat-safety measures on Friday as a prolonged and potentially record-setting heat wave gripped much of the central and eastern regions ahead of Independence Day celebrations, with millions of residents remaining under heat alerts and authorities warning of a heightened risk of heat-related illness.
The National Weather Service said more than 185 million people were under heat alerts as a persistent high-pressure system, commonly known as a heat dome, pushed temperatures into the upper 90s and low 100s Fahrenheit across large parts of the country. Combined with high humidity, heat index values were forecast to reach as high as 115 degrees Fahrenheit in some locations.
Federal, state and local officials urged people attending July 4 events to stay hydrated, limit strenuous outdoor activity during the hottest hours of the day, seek air-conditioned spaces when possible and check on older adults, young children and others considered especially vulnerable to extreme heat. Health authorities also warned that unusually warm overnight temperatures could reduce opportunities for the body to recover from prolonged heat exposure.
Cities across the affected region expanded public health responses. New York City opened hundreds of cooling centers and deployed mobile assistance vans, while Chicago encouraged residents to request welfare checks for vulnerable individuals through its 311 service. Washington activated additional cooling resources and hydration stations as large crowds were expected for holiday events.
Some municipalities altered or canceled outdoor celebrations because of the dangerous conditions. Philadelphia canceled its Salute to Independence Parade after temperatures tied a daily record earlier in the week, while several communities in New Jersey and upstate New York also called off planned July 4 events. Boston delayed entry to its annual riverside fireworks celebration to reduce heat exposure during the day.
The Centers for Disease Control and Prevention advises that heat stroke is a medical emergency requiring immediate treatment. Symptoms can include confusion, loss of consciousness and a body temperature above 103 degrees Fahrenheit, while heat exhaustion may involve dizziness, nausea and heavy sweating. Officials said prompt recognition and treatment are critical during extended periods of extreme heat.
Forecasters said dangerous heat was expected to persist through the holiday weekend in many eastern states before gradually shifting westward, with public health agencies continuing to monitor conditions and urging residents to follow local advisories as emergency measures remained in place.
