Abstract Inadequate flood risk management highlights the need to better understand when and where extreme floods occur. Existing wisdom explains the geographic likelihood of these floods, but falls short in determining when they can be anticipated. Here we identify synoptic origins (referring to large‐scale weather patterns and the associated rainfall processes) of extreme floods by analyzing a large catalog of flood‐producing storms over the North China Plain. The most extreme floods are associated with a northward and westward extension of the Subtropical High, providing favorable synoptic conditions for predecessor rainfall processes, despite their relatively low frequency of occurrence. Low‐level moisture convergence modulated by both regional topography and synoptic forcing dictates the spatiotemporal variability of extreme rainfall. We reveal a critical dependence of basin‐scale flood controls on synoptic origins of extreme floods. Our analysis provides process‐driven insights into the tail behavior of flood peaks that can inform flood risk management.

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