We developed a simple algorithm for detecting hot spots using Sentinel-2A data, modifying a method for Landsat 8 data. The empirical hot spot detection equation was developed using apparent spectral reflectances at band 8a (0.87 μm) and band 12 (2.2 μm). Due to the improved spatial resolution, false detections often occur in inclined flat surfaces, such as roofs and solar panels. To avoid such false detection, we defined a new detection equation with empirical thresholds additionally using an apparent spectral reflectance at band 11 (1.6 μm) based on typical spectral characteristics of surface materials and the blackbody assumption. The proposed algorithm successfully reduced the occurrence of false detection in urban areas.