With leading market-implied odds clustered tightly between 22–24°C (each near 19–20%), traders reflect substantial uncertainty in short-range ensemble forecasts for Seoul’s minimum temperature on July 20. The East Asian summer monsoon’s variable moisture flux, combined with urban heat-island effects and potential nocturnal cloud cover, modulates radiative cooling and creates modest day-to-day spread in model guidance from agencies such as the Korea Meteorological Administration. Historical July minima average near 22–23°C, providing a climatological baseline that current conditions have not yet deviated from decisively. Fresh observational data and updated model runs over the next 48 hours remain the key near-term catalysts that could consolidate or further disperse these probabilities.