Trader consensus on Seoul's June 25 minimum temperature shows tight clustering around 18–21°C, reflecting genuine short-range forecast uncertainty rather than strong model agreement. Primary drivers include variable cloud cover and radiative cooling overnight, modulated by the early East Asian summer monsoon pattern and weak pressure gradients that limit advection from the Yellow Sea. Recent global model runs (GFS, ECMWF) diverge on nocturnal boundary-layer mixing and urban heat retention, with clearer-sky scenarios favoring the lower end and increased moisture supporting mid-20s readings. KMA updates and next 48-hour ensemble guidance will likely shift implied probabilities ahead of resolution.