**Trader consensus has converged on 21°C as the daily maximum for Seoul/Incheon on October 3, 2026, driven by verified observational data from regional weather stations showing afternoon peaks at that level under overcast skies.** Early October climatology in the Seoul metropolitan area features highs typically ranging 20–23°C amid transitioning autumn patterns, with light southeasterly flow and high pressure supporting stable, dry conditions that limited further warming. Model guidance and surface observations aligned closely on this threshold throughout the day, with no significant convective activity or warm advection to push readings higher. Official resolution will hinge on the final Korea Meteorological Administration daily maximum from the Incheon or Seoul reference station; only an unexpected post-peak reading or data revision could alter the outcome at this stage.