Urban areas are already experiencing impacts of a changing climate including increased temperatures, flooding, and extreme storms. These impacts are projected to increase in frequency and magnitude over the next century, leading many cities to develop plans to adapt and prepare for these challenges. Increasing tree canopy is often considered in urban climate change adaptation plans, where trees can help reduce local heat island effects, control storm water, and improve air quality. Although urban trees can be an important part of adaptation solutions, they also can be vulnerable to the impacts of climate change. Harsher summer temperatures, potential summer droughts, heavy winds, flooding, and increased pests and diseases can all stress urban trees. These urban trees may be experiencing stress from improper planting, restricted rooting conditions, road salt, and air pollution already, and therefore extremely vulnerable to climate change.