The Extreme Heat as a Climate-Health Hazard brief from the National Academy of Medicine highlights the growing threat of extreme heat due to climate change. Global temperatures have risen approximately 2 °F since preindustrial times, intensifying the frequency and severity of heatwaves. Heat exposure leads to a range of health risks, from dehydration and heatstroke to exacerbation of chronic illnesses and mental health impacts. Vulnerable populations include older adults, children, outdoor workers, and those without air conditioning. In 2023, the U.S. recorded over 2,300 heat-related deaths. The brief calls for urgent public health interventions, including early warning systems, cooling infrastructure, and community outreach. It emphasizes that human-driven climate change is a major contributor to increasing heat-related mortality and urges systemic, equity-focused adaptations to protect public health.