Heat-Related Emergency Visits Surged in the Record-Hot U.S. Summer of 2023

May–September 2023 was the hottest warm season ever recorded in the United States. Heat can harm anyone, but some people face more risk: older adults, children and teens, people with health conditions, pregnant women, outdoor workers, people with little access to cooling, and those in low-income communities. Extreme heat can also flood emergency departments (EDs) and strain health systems.

CDC used National Syndromic Surveillance Program data to compare daily heat-related illness (HRI) ED visit rates in the 2023 warm season with those of 2018–2022, across the 10 HHS regions.

Steps health departments can take to prevent heat-related illness. CDC.

Key findings

• In 2023 there were 119,605 heat-related ED visits recorded; 92% came during May–September.
• The average warm-season rate was 180 per 100,000 ED visits, up from 151 in 2018–2022.
• July and August averaged 303 per 100,000 ED visits, versus 97 in May, June and September — a risk 3.07 times higher. In 2018–2022, July–August risk was only about twice that of the other months.
• Every HHS region had at least one day above the 95th percentile of its 2018–2022 daily rates. In regions 6 and 9, rates stayed above it for 16 and 18 consecutive days in July.

Who was affected

Adults 18–25 and 26–54 had about 2.5 times the risk of those under 18.

Where

Heat-related ED visits per 100,000 ED visits, warm-season average.

Compared with Region 2, the risk in regions 4, 6, 7 and 9 in 2023 was 1.5–2.5 times what it had been in 2018–2022.

• In regions 4, 6, 7 and 9, more days exceeded the 95th percentile than in any earlier year of the study.
• In Region 6, 56 days — more than a third (37%) of the warm season — were above it.
• Regions 6 and 7 had their highest single-day rates since 2018.

CDC issued public health alerts through its Epidemic Information Exchange on June 30 and August 23, 2023, after seeing high levels of heat-related ED visits.

What it means

• The pattern — men and adults 18–64 most affected — matches other studies. Children had the lowest rates here, but other research suggests they may be affected at rates similar to adults in some areas.
• Outdoor workers deserve particular attention given how many working-age adults sought care; frontline workers such as firefighters may be at especially high risk.
• Regional differences may reflect differences in acclimatization, behavior and adaptation, and understanding them can guide heat action plans and heat alerts tuned to local health data, such as HeatRisk — a 7-day, 5-level health-based heat forecast from NOAA's National Weather Service and CDC.
• Access to cooling matters. Even in the South and Southeast, where air conditioning is common, people may lack cooling because of energy costs or power outages. HHS programs that help pay home energy bills and that track people who depend on electricity-powered medical equipment during outages can protect people at risk. Communities with many at-risk residents, limited health care and persistent heat (heat islands, few green spaces) may be especially vulnerable.
• Near–real-time tracking — like CDC's Heat and Health Tracker — helps agencies time warnings and prevention. With climate change bringing longer, hotter and more frequent heat waves, heat-related illness will remain a major public health concern.

Limitations

1. The surveillance data aren't nationally representative, and participation varies by region.
2. Veterans Affairs facilities weren't included, and the rate is a share of ED visits, not of the population.
3. Regional figures can hide local variation.
4. The COVID-19 pandemic changed ED use, which may have affected earlier-year rates.
5. Only ED visits were counted, so heat illness treated elsewhere was missed — likely an underestimate.

Sources

Based on Vaidyanathan A, Gates A, Brown C, Prezzato E, Bernstein A, "Heat-Related Emergency Department Visits — United States, May–September 2023," Morbidity and Mortality Weekly Report, Centers for Disease Control and Prevention; a work of the United States government in the public domain. The imported copy was cut off in two places; the missing text and the report's tables were taken from the same report's full text in PubMed Central (PMC11037437).