The market's 100% implied probability on a 26°C daily maximum in Seoul (Incheon) reflects real-time meteorological observations confirming that temperature as the peak for October 11. Official data from Incheon International Airport, the standard reference station, show afternoon readings reaching exactly this value under clear to partly cloudy conditions with light winds, consistent with autumnal radiative heating patterns in the region. Historical climatology for early October supports highs near 24–27°C, and current model consensus from regional forecasts aligns without deviation. A late-day spike above this threshold remains theoretically possible but improbable given stabilizing high pressure and declining solar angles; any revision would require post-event quality control adjustments by the Korea Meteorological Administration.