In the United States in 2023, record-breaking heat waves had significant public health implications, particularly affecting vulnerable groups such as the elderly, children, pregnant women, outdoor workers, and those with preexisting health conditions.

The Centers for Disease Control and Prevention (CDC) analyzed data from the National Syndromic Surveillance Program to assess the impact of these extreme temperatures, comparing the frequency of heat-related illness (HRI) emergency department (ED) visits from May to September of 2023 against the same months in 2018–2022.

Throughout 2023, a total of 119,605 HRI ED visits were documented, according to data published in Morbidy & Mortality Weekly Report. During the warm-season months, daily HRI ED visit rates not only peaked in several U.S. regions but also maintained elevated levels for extended periods. Notably, males aged 18–64 were more frequently treated for HRI in EDs. The CDC utilized the Epidemic Information Exchange system to issue multiple public health alerts addressing the surge in ED visits due to HRI.

This ongoing public health issue underscores the need for vigilant, near real-time monitoring of weather conditions and associated health outcomes to enhance the effectiveness of public health communications and preventive measures against extreme heat.

This study’s insights into the patterns of heat-related illnesses across various U.S. regions and demographic groups are instrumental for guiding future public health strategies aimed at reducing HRI risks and improving community resilience against extreme heat conditions.