Coastal South China is frequently exposed to substantial rainfall within fronts-free environments during the presummer rainy season, which recurrently leads to severe disasters due particularly to the heavy short-term rainfall (HSR). The present study is motivated to identify the HSR hotspots over coastal South China through 10 notorious episodes of warm-sector heavy rainfall, with emphasis on the mesoscale features linking with the HSR hotspots. These episodes suggest complex rainfall features in the occurrence frequency and intensity. HSR mainly occurs rather over the coastal areas than the windward piedmont farther inland, and contributes over 80% to the rainfall accumulation in the regions of Yangjiang and Shanwei. Mesoscale topographies in both regions play an important role in the presence of HSR hotspots, but in different ways. Convergence perturbation line related to the inland mountains migrates southward, and enhances the preexisting convection along the coast resulted from the differential surface friction between land and ocean as well as small hills, which is the primary cause for the high frequency of HSR in coastal Yangjiang. While concave terrain drives cyclone-like perturbation, modulating the convection activity prior to the presence of HSR over Shanwei region. A cold dome induced by the previous convection dominates the mesovalley, furthering the subsequently convective enhancement at coastal zone. Collectively, both inland mountains and ocean-to-land friction regulate the mesoscale surface processes by governing the convergent wind perturbations and upscale convective growth, responsible for the HSR hotspots over the low-altitude coastal areas.