The world population increasingly lives in cities, implying the critical need for a better understanding of the complexity of the climatic context of urban agglomerations and their inner microclimatic characteristics. The urban microclimate is not only relevant to people's experience of outdoor thermal conditions in the cities: The temporal and spatial variance of urban microclimate is also causally related to the thermal performance of buildings. These considerations represent the main motivations behind a number of ongoing research efforts: To which extent do microclimatic conditions in cities differ from those in the surrounding rural environment? What physical features of the urban environment could explain the variance of urban microclimate? What measures could mitigate adverse developments in microclimatic conditions in the cities? Can computational tools and models contribute to prediction the effects of mitigation measures?