In this chapter we will review and evaluate the climatic and ecological parallels between urbanization and climate change, with an emphasis on temperature and its effects on terrestrial ectotherms, a group of organisms thought to be particularly sensitive to climate change. We will summarize patterns of urban warming and how they relate to global climate change projections, then discuss the potential strengths and limitations of urban climates as a source of insight into biotic responses to climate change and highlight future research directions. Future work will benefit from explicit consideration of the mechanisms by which urbanization and urban warming drive ectotherms’ body temperatures and activity periods. Urban ecosystems may provide a valuable first approximation of the dramatic effects of warming on certain terrestrial systems, and continued advances in urban thermal biology will promote a mechanistic understanding of how organisms use, respond to, and adapt to the unique thermal landscapes of cities.