<p>Record-breaking rainfall affected southern China in April 2024, causing substantial socioeconomic losses. Using station observations and ERA5 reanalysis, this study investigates the intraseasonal variability of this event and the roles of Pacific sea surface temperature (SST) and the North Atlantic Oscillation (NAO). Although April-mean rainfall over southern China has exhibited a long-term decreasing trend since 1979, rainfall in 2024 reached a record high and featured pronounced intraseasonal wet–dry–wet fluctuations, denoted as P1, P2, and P3. Dynamical analyses show that anomalous vertical motion was central to these intraseasonal variations. Exceptionally deep forced ascent, associated with low-level Ekman pumping and upper-level divergence, sustained persistent rainfall during P1 and P3, whereas anomalous subsidence suppressed precipitation during P2. Moisture budget diagnostics further indicate that processes associated with ascending motion dominated the intraseasonal fluctuations of this extreme event. Statistical analyses identify distinct oceanic and atmospheric precursors to the April 2024 rainfall extreme over southern China. Warm SST anomalies in the tropical eastern Pacific may have favored enhanced upward motion and increased April rainfall over southern China, while the intraseasonal variability of the event was linked to the NAO at lead times of 10–30&#xa0;days, likely through Rossby wave train propagation and the resulting anomalous circulation over southern China. These results improve understanding of the April 2024 extreme rainfall event over southern China and its intraseasonal variability, with implications for subseasonal prediction of preseason rainfall in the region.</p>