Recent Korea Meteorological Administration short-range guidance points to a maximum of 33 °C in the Seoul-Incheon area on 19 August under mostly cloudy skies with minimal precipitation, yet market-implied odds cluster tightly around 29–30 °C because traders weigh coastal moderation from Incheon’s sea-breeze circulation and lingering moisture from mid-August showers that can suppress peak heating. Day-to-day variability arises from subtle differences in low-level cloud thickness, which reduces incoming solar radiation, and from the precise timing of any weak frontal passage that could shave 1–2 °C off the daily high. Ensemble spread in regional models remains several degrees wide this far ahead, creating the balanced 29 °C versus 30 °C probabilities; an updated 00 UTC run or clearer satellite trends on 18 August could quickly shift the distribution toward 31 °C or higher if subsidence strengthens.