**Clear skies and northerly flow following a cold frontal passage have locked in a daytime maximum of 21 °C at Incheon International Airport, the reference station for this market.** Official Korea Meteorological Administration guidance and multiple model runs converged on this value after a roughly 5 °C day-to-day drop from late September, with hourly observations confirming the peak under light to moderate northwest winds and negligible cloud cover. Historical early-October averages near 21–22 °C provide additional context for the tight clustering around this level. With the sun now low and temperatures already falling, only an improbable late-afternoon measurement revision or station-specific microclimate difference would alter the recorded high.