Climate change is increasing the frequency of heat waves and heat-related health issues, particularly in cities due to the urban heat island effect. While government entities see the value of utilizing the urban forest (UF) to reduce heat exposure in cities, practical and community-based considerations focused on UF heat mitigation are poorly understood. To address this gap, this study conducted 34 interviews with urban tree professionals (e.g., city arborists, UF researchers, non-profit urban foresters) across the United States to explore the practicalities of using specific tree species for improving heat-related health, and to inform future UF research and interventions. The primary findings were: 1) there are knowledge gaps on tree cooling potentials despite perceived importance of cooling; 2) despite evidence of climate warming, tree survival rather than cooling potential remains a priority; 3) climate change is altering habitat suitability and environmental stress tolerance, and therefore tree cooling potential; 4) funding can be better invested in tree maintenance than in new plantings; and 5) quantification of public health benefits of the UF may help increase advocacy for UF funding and public education. Our findings reveal that operationalizing tree cooling at the species-level is fundamentally challenging, particularly because climate warming increases the need for understanding species-specific cooling, yet there is uncertainty about which trees will survive in future climates. These challenges require continued multidisciplinary collaboration, particularly for researchers who are working at the intersection of public health, urban forestry, and climate change adaptation strategies.