Trader consensus for Seoul's September precipitation shows tight clustering around 75–250 mm bins due to substantial forecast uncertainty at the month's outset. Developing El Niño conditions typically suppress rainfall through an anomalous anticyclone over East Asia and altered tropical cyclone recurvature, reducing moisture transport from the western North Pacific subtropical high. Counterbalancing factors include potential late-season typhoon landfalls or lingering frontal systems, which historically boost totals in the 150–200 mm range. Short-term model runs indicate initial central-region rains, but September outcomes hinge on evolving steering patterns and monsoon withdrawal timing, with new extended-range updates from agencies like KMA expected to refine probabilities.