Extreme Heat: Leading Cause of Weather-Related Deaths in U.S.

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This post summarizes key takeaways from the APHA 2025 workshop “Extreme Heat & Health: Clinical and Public Health Strategies for Prevention and Action.” It explains why extreme heat now causes more deaths in the U.S. than any other weather hazard, who is most at risk, how heat injures the body, and practical prevention strategies—ranging from personal cooling to community frameworks like BRACE—that health professionals and communities can deploy immediately.

Why extreme heat is the most lethal weather risk and why it’s getting worse

Extreme heat has overtaken other weather events as the leading cause of annual weather-related deaths in the United States. The trend is accelerating as global temperatures rise.

A 2024 JAMA analysis documented a steady climb in U.S. heat-related deaths from 1999 to 2023. There was a particularly sharp increase after 2016, underscoring an urgent public health challenge linked to climate change.

How heat harms the body and who pays the price

Heat stress exacerbates chronic cardiovascular and respiratory conditions and worsens mental health. As Dr. Logan Harper explained at the workshop, the physiological burden of heat can tip vulnerable patients into rapid decline.

Certain commonly used medications—such as diuretics, beta blockers, antihistamines, and some psychiatric drugs—can impair thermoregulation and hydration. This increases risk.

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Clinical signs to recognize:

  • Heat exhaustion — heavy sweating, cramps, weakness, dizziness, and possible fainting.
  • Heat stroke — hot, dry skin or profuse sweating followed by collapse, confusion, seizure, and possible organ failure; mortality can reach up to 80% without rapid treatment.
  • Who is most vulnerable and why targeted action matters

    Vulnerability to extreme heat is not evenly distributed. Most heat-related illnesses and deaths are preventable if interventions target highest-risk groups and places.

    Priority groups and hotspots

    Higher-risk populations include:

  • Older adults and infants/children
  • Outdoor workers (construction, agriculture, delivery)
  • People living without reliable air conditioning or in low-income housing
  • Residents of urban heat islands where built surfaces retain heat
  • Those taking medications that reduce heat tolerance
  • Effective prevention: from personal precautions to community planning

    Prevention requires both immediate, practical measures and longer-term planning. Clinicians and public health professionals can reduce harm by combining individual counseling with community-level heat action plans.

    Practical, evidence-based steps

    Personal and household actions:

  • Increase fluid intake and avoid alcohol during heat waves.
  • Use air conditioning or seek cooling centers when temperatures rise.
  • Limit strenuous outdoor activity during hottest hours; reschedule work when possible.
  • Review medications with clinicians to identify drugs that heighten heat risk.
  • Recognize early symptoms and cool immediately—move to shade, apply cool water, and seek medical care for severe signs.
  • Community and clinical strategies: Implement heat preparedness using the BRACE (Building Resilience Against Climate Effects) framework to assess risk and engage stakeholders. Build adaptive interventions such as cooling centers, heat-health warnings, occupational protections, and urban greening to reduce heat islands.

    The role of health professionals: be a climate and health ambassador

    Ben Fulgencio-Turner of ecoAmerica urged health professionals to use their trusted voices to elevate heat awareness and advocate for policies that protect public health from climate risks.

    Clinicians are uniquely positioned to counsel patients and coordinate with public health systems.

    They can push for structural solutions—like improved housing, heat-safe workplace policies, and expanded cooling access—that will save lives.

    Immediate cooling and targeted outreach during heat events, paired with long-term resilience planning, can dramatically reduce the rising toll of heat-related illness and death.

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