In Heat Advisory I examine climate change from a broad public health perspective, where health includes mental and social well-being in addition to climate-related changes in diseases. I begin from baselines defined by worldwide selected causes of death and risk factors for disease as seen partially through the lens of the United Nations Sustainable Development Goals to discuss how climate change will affect health. I draw primarily on a broad cross-section of the peer-reviewed literature and governmental reports. In addition to heat-related illnesses, I discuss infectious diseases including dengue, malaria, and Zika; effects on agriculture and the potential for famine; rising sea level, severe weather, and environmental refugees; anticipated effects of climate change on air quality with a focus on ozone and asthma; the influence of climate on violence, conflict, and societal disruption; and, finally economic considerations related to health. Following fundamental public health and medical practices, I discuss, primary prevention in terms of mitigation of climate change by reducing greenhouse gas emissions, and secondary prevention, by adapting to climate change. Health professionals have a professional responsibility to affect political will and foster the extensive stakeholder involvement required to tackle climate change, the “greatest public health opportunity” of this century.