Climate change is the greatest global health threat of the twenty-first century, yet it is not widely understood as a health hazard by primary care providers in the United States. Aside from increasing displacement of populations and acute trauma resulting from increasing frequency of natural disasters, the impact of climate change on temperature stress, vector-borne illnesses, cardiovascular and respiratory illnesses, and mental health is significant, with disproportionate impact on underserved and marginalized populations. Primary care providers must be aware of the impact of climate change on the health of their patients and advocate for adaptation and mitigation policies for the populations they serve.