**October precipitation totals in Seoul are shaped primarily by the transition from the East Asian summer monsoon to drier autumn conditions, with cold frontal systems from the Asian mainland delivering most rainfall.** Historical normals from the Korea Meteorological Administration (1991–2020) place the monthly average near 52 mm, concentrated in light rain events tied to roughly one frontal passage per week. Each system typically brings brief, modest precipitation followed by clearer periods, limiting accumulation unless fronts stall or interact with residual moisture. Recent interannual variability has been notable, with some Octobers under 25 mm and others exceeding 100 mm depending on frontal frequency and any lingering Pacific influences. With no strong typhoon signals or anomalous large-scale patterns currently indicated for early October 2026, trader consensus clusters around the 40–70 mm range, reflecting the balance between typical frontal activity and the inherent uncertainty in monthly rainfall totals.