The effects of the environment on human health have been a concern in society for centuries, and significant progress has been made in promoting public health by tackling environmental hazards. Similar to how sanitation and flood mitigation have become critical components of and indicators for urban life, we posit that urban heat poses a significant risk to human physical and mental health. Reflecting on origins of contemporary Western urban design, we see a significant amount of energy dedicated to addressing both physical and mental health through changes in urban design, ecosystems, and climate. Building from this, we advocate for a reframing of current issues in urban design that considers how urban climate affects our physical and mental health. This theoretical approach presents a fresh perspective on the intersection of design, climate, and mental well-being. It delves into the pathways that lead from elevated air temperature, exposure to sunlight, and interaction with natural environments to potential crises in mental health. We use urban climate as a lens through which we examine how urban design and mental health are connected and what solutions might exist to address previously identified urban design issues while also improving the mental health of communities.