Official Korean Meteorological Administration forecasts and real-time observations for August 16 indicate a daily maximum near 27°C in the Seoul-Incheon area, with persistent rain, easterly flow, and cloud cover suppressing daytime heating below seasonal norms around 30–31°C. High humidity and precipitation probability above 60% further limit convective warming and solar radiation, aligning trader consensus with this measured threshold. The 100% market-implied probability reflects strong alignment between model guidance and on-site data, though an unexpected late-day clearing or shift in steering winds could allow brief warming above 27°C before resolution.