A number of recent challenges in the realm of microclimatic studies are set on a better understanding of the Urban Heat Island (UHI) phenomenon. Particularly, UHI is believed to be a characteristic consequence of urban microclimate evolution. Changes in urban microclimate, and corresponding higher air temperatures within urban domains, are believed to have cardinal consequences on the issues such as the thermal comfort of the city dwellers, mortality rate, local air quality, and energy demand of buildings. Generally speaking, the undesired thermal circumstances in the urban environment are caused in part by human-induced changes introduced in land use and land cover (building agglomeration density, presence and extent of green areas and bodies of water), and corresponding environmental emissions (anthropogenic heat production). Currently, there is a lack of practical assessment approaches focusing on the formation of UHI while considering a relatively comprehensive range of factors of the built environment. In this context, the present contribution summarizes the results of a multiyear effort concerned with the extent and implications of the UHI phenomena in the city of Vienna, Austria. For this purpose, high-resolution data streams across five key locations are obtained, structured, and analyzed. This allowed for an objective assessment of the locationdependent manifestations of microclimatic circumstances across distinct low-density suburban and high-density urban typologies in Vienna. Subsequently, a systematic framework is developed to identify essential properties of the urban environment that are hypothesized to influence UHI and the urban microclimate variation. These properties pertain to both geometric (morphological) and semantic (material-related) urban features. Once these features are derived, the existence and extent of the correlations between urban microclimate variation and the urban features are explored. These statistically significant correlations further provided a useful basis toward developing empirically-based predictive models. These models are expected to support the understanding and prediction of local differences in the urban climate. The contribution presented in this dissertation was developed within the framework of a - recently completed - European project (Central Europe Program, No 3CE292P3). The framework was developed in part through extensive collaboration among the project team members and represents a valuable resource of scientific information on the links between the urban microclimate variation and essential driving factors to this variation.