Tropical cyclone rainfall extends inland

Tropical cyclone (TC) rainfall, which is typically more intense over the ocean, has increasingly caused devastating floods in coastal regions in recent decades. Regions beyond 100 km inland from coastlines often lack adequate preparedness for TC-induced flooding, underscoring the need to assess whether global shifts in terrestrial TC rainfall, particularly heavy rainfall, have occurred. Here, we show that TC rainfall has extended inland globally from 1980 to 2023. Specifically, along the continental coasts of the Northern Hemisphere, the landward extent of TC heavy rainfall (≥30 mm per 3 h) has increased at a rate of 3.8 ± 1.8 km per decade (95% CI). Notably, the statistical significance of this global trend is robust, regardless of spatial constraints on TC rainfall or the trajectories of coastal TCs. Observations and model simulations suggest that nearshore sea-surface temperature (SST) warming is closely linked to this landward extension, likely by amplifying the land–ocean contrast in terms of friction-related dynamical responses. Coastal urbanization may further enhance this extension when coupled with SST warming. As coastal cities continue to extend inland, the landward extension of TC heavy rainfall could exacerbate inland population exposure and potential flood risk. This study shows that tropical cyclone heavy rainfall has extended inland along the coasts of the Northern Hemisphere with a rate of 3.8 km per decade since 1980. Nearshore sea-surface warming drives this expansion, with coastal urbanization further amplifying the effect. These findings highlight increasing flood risk for inland populations as cities grow.