<![CDATA[The modulation of rainfall extremes by the Madden–Julian Oscillation (MJO) over Indonesia and the Maritime Continent is well established, but less is known about how consistently this relationship is represented in documented large-scale flood-impact records. This study provides an event-based assessment of active MJO phases 3–5 on high–very high (HVH) rainfall associated with large-scale flood events across seasonal rainfall zones (ZOMs). Flood records from 2008–2024 were linked with reconstructed daily rainfall data from 107 rain-gauge stations and daily Real-time Multivariate MJO index information. Large-scale flood events were defined based on spatial and temporal extent, while HVH rainfall was classified as rainfall above the 75th percentile and evaluated using maximum one-day and five-day accumulated rainfall. The results show that 210 of 577 HVH rainfall-event records, or 36.4%, occurred during active MJO phases 3–5. Active-MJO conditions occurred in 22.2% of one-day HVH rainfall events and 48.6% of five-day accumulated HVH rainfall events. During DJF, active MJO phases 3–5 occurred in 55.1% of five-day accumulated HVH flood-associated events, compared with a seasonal five-day-window baseline of 47.6%, corresponding to a modest enrichment ratio of 1.16. These findings indicate that active MJO phases 3–5 provide complementary information on multi-day HVH rainfall accumulation, although their contribution varies substantially by season and should be interpreted relative to the seasonal background occurrence of the MJO.]]>
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