Monsoon–ocean competition shapes the record-low 2023 western North Pacific tropical cyclone season

Tropical cyclone (TC) activity over the western North Pacific (WNP), the most active TC basin worldwide, is generally viewed as being controlled by remote oceanic forcing, especially the El Niño–Southern Oscillation. However, oceanic forcing alone cannot fully explain variability in TC genesis. Here we show that the record-low WNP typhoon season of 2023 emerged from strong seasonal asymmetry rather than uniform suppression. Despite unfavorable large-scale ocean conditions, summer TC genesis frequency remained near climatology because a weakened Indian summer monsoon (ISM) triggered an atmospheric Kelvin-wave response that induced a WNP cyclonic circulation anomaly. This circulation offset the ocean-forced anticyclone and maintained environmental conditions favorable for TC genesis. In contrast, remote ocean forcing dominated during autumn, producing unprecedented suppression and driving the seasonal minimum. These results highlight a pathway by which ISM variability can counteract basin-scale oceanic forcing and regulate WNP TC variability, with potential implications for improving TC prediction.