Data on the Urban Heat Island (UHI) phenomenon are systematized. The main causes of the UHI and its possible consequences have been researched. The main reason for the increase in urban air temperature is the formation of fundamentally different temperature-humidity and air conditions in the urban development due to a change in the land use structure compared to the adjacent territory. Heat and mass transfer processes in the urban environment are closely interconnected. As settlements grow, the UHI effect is increased. In a temperate climate with hot, dry summers, the mechanisms of the UHI are not sufficiently studied. It is shown that a new paradigm of urban planning is needed, based on the harmonious relationship between man and the environment. Urban planning strategies aimed at the broad application of green infrastructure can significantly reduce the energy demand of cities in the summer while providing new green areas for people. The reduction is especially distinctly in megacities in which residential apartment buildings make up a significant part of the development. TIt is necessary to monitor the outdoor climate at various points in the city to determine the actual meteorological characteristics. The measurements serve as a baseline for mathematical simulation of the urban climate. According to the research results, concrete proposals can be made to form a comfortable energy-efficient environment for city residents. Such research is relevant and promising.