This paper presents the problem of the increasing negative impact of urban heat islands (UHI) on urban residents based on land surface temperature (LST). It is assumed that water bodies in the agglomeration remain cooler than the air and surrounding urban areas. The study aimed to determine the impact of water bodies and surrounding areas covered by trees on the temperature of an urban area and to minimise the impact of UHI on the life quality of people in the temperate climate zone at day temperatures 25°C (W day) and 29°C (H day). In the adopted research methodology, 167 reservoirs, larger than 1 ha, located within 300 m of urban areas, were analysed. Satellite thermal imagery, spatial land use data (Corine Land Cover), and local land characteristics were used. The average temperature of the reservoirs was appropriately at 4.69°C on W day and 1.9°C for H day lower than in residential areas. The average temperature of areas at a distance of 30 m from the reservoirs was 2.69°C higher onWand 0.32°C higher on H than the water of the reservoirs. The area covered by trees was 0.52°C lower on W day and 0.39°C lower on H day than the residential areas located at a distance of 300 m from the reservoir. On terrestrial areas, the lowest temperature was observed in the area covered by trees within 0–30 m from reservoirs both on warm and hot days. Based on the results of this study, UHI mitigation solutions can be suggested.