The intense development of cities and related replacement of vegetated areas with impervious surfaces contributed to the intensification of the urban heat island effect, which is a hazardous phenomenon for humans. In this study, the spatial structure of the surface heat and cold island (SHI and SCI, respectively) in the Górnośląsko-Zagłębiowska Metropolis (GZM), the most urbanized and populated area in Poland, is investigated using four Landsat 8 satellite images recorded in the summers between 2015 and 2019. The satellite images processed to the land surface temperature (LST) and the Corine Land Cover 2018 (CLC 2018) classification were used to calculate indicators of the spatial extent and intensity of SHI and SCI. Their spatial extents in the GZM ranged from 15.4 to 16.4% and 12.2–19.4%, respectively, depending on the analyzed days with a large percentage of the agricultural areas within the SHI boundaries. Therefore, an original approach to delineate the surface urban heat island (SUHI) is proposed. This approach reduced the extent of the GZM SHI by 2.9 to 2.0%, depending on the day. In the GZM, more than 70% of the SHI consisted of discontinuous urban fabric and industrial or commercial units. Heat island indices recognized the spatial structure of SUHI as an archipelago. Vegetation and crops constituted 90% of the SCI, and these land cover types explained most of the SCI variability over time compared to the SHI. The vegetation expanded, and its characteristics continually changed during the summer season. Moreover, vegetation was more sensitive to changes in meteorological conditions than impervious surfaces. The LST was most strongly correlated with the percentage share of artificial areas in the GZM districts. In turn, the correlations between LST and forest and semi natural areas were much weaker when precipitation occurred before the recording of satellite images. The intensity of SUHI in the GZM ranged from approximately 5 to 9 °C depending on the date and the method of identifying urban and nonurban areas.