The paper deals with the Prague Heat Island, the climatic phenomena typical for all big cities. The attention is paid to its size, respectively intensity, presented is also the time evolution in the last 50 years and the expected development until the half of the next decade.
Next to it, the biometeorological aspect of the phenomena is also mentioned through the physiological equivalent temperature, which is used for the first time in such a context. Considering that the big motivation for deepening the knowledge about Prague Heat Island is project ""UHI"", financed by the FP7 EU program in the scope of the ""Central Europe Program"", the paper mentions also the basic information about this project with a focus on Prague.