Trader consensus around a 20°C high in Seoul-Incheon on October 5 reflects consistent model outputs and observational data showing peak afternoon temperatures reaching this level under mostly clear to partly cloudy skies with moderate northwest winds. Official forecasts from sources aligned with NOAA and regional models indicate a daytime maximum near 19–20°C, consistent with seasonal October climatology for the region and recent high-pressure dominance suppressing cloud cover and precipitation. This positioning draws from real-time surface observations and ensemble agreement on minimal variability. A realistic challenge could arise only from an unexpected late-day surge in marine influence or model error in boundary-layer mixing that trims the peak by 1°C, though current data make such shifts unlikely before resolution.