October precipitation in Seoul averages 50–55 mm under 1991–2020 normals, driven primarily by weekly passages of cold frontal systems from the Asian continent that deliver light to moderate rain during the transition from summer monsoon to drier winter conditions. Strong El Niño development through late 2026 introduces additional uncertainty, with models showing mixed signals for East Asian autumn rainfall that could shift totals above or below the historical range depending on the precise timing and intensity of fronts. Korea Meteorological Administration outlooks for early October through November currently favor near-normal totals for the Seoul region, though interannual variability remains high given the limited number of rain days (typically 5–7) and potential for localized heavier events. Updated dynamical forecasts and observational data in the coming weeks will refine trader assessments of whether totals cluster near the 40–70 mm bins or deviate toward drier or wetter extremes.