Increasing favorability for intense tropical cyclone activity in the northern South China Sea

The South China Sea (SCS) is one of the most active marginal seas for tropical cyclones (TCs) worldwide and a key region for TC hazards along the coasts of southern China, Philippines and Vietnam. However, the drivers of long-term changes in intense TC development in this region remain unclear. Here, we show that the number of TCs reaching Category 3-5 intensity has increased significantly, with more occurring in the northern SCS. This change is primarily linked to an increasing contribution of western North Pacific TCs entering through the Luzon Strait, which experience weaker land-induced weakening than those crossing the Philippine archipelago and retain greater intensity for subsequent development. After entering the SCS, reduced ocean cooling and enhanced oceanic and atmospheric conditions have increased the environmental favorability for intense TC development in the northern SCS. These results highlight the role of regional ocean-land-atmosphere interactions in reshaping where TCs reach high intensities.