Several studies have documented a close relationship between forest fires and the instability of the soil-vegetation system. Furthermore, repeated wildfires, especially characterized by extreme severity and intensity, can induce hydrological and geomorphological effects that persist over several years, e.g., the temporary erosion rate intensification and the susceptibility increase of most significant downslope soil movement. This study analyzes the close relationship between wildfires and soil instability by examining the mega-fire in July 2021 in the Montiferru - Planargia region (Sardinia, Central Mediterranean). The proposed multiscalar methodology provides management and plan indications to mitigate potential damages caused by extreme wildfire, especially in areas with high susceptibility from a hydrogeological perspective, using physical models supported by open geodata in a GIS-based workflow.