Weather model ensembles for Busan reveal modest uncertainty in nocturnal radiative cooling and boundary-layer mixing ahead of August 28, keeping market-implied odds clustered around 24–26 °C for the daily minimum. Persistent high pressure supports mostly clear skies that favor greater heat loss overnight, while variable sea-surface temperatures in the Korea Strait and light southerly flow limit how far inland cooling extends. Ensemble spreads from the Global Forecast System and European Centre for Medium-Range Weather Forecasts show minimum-temperature solutions differing by 2–3 °C depending on exact cloud timing and wind direction. Historical August lows in Busan average near 23–25 °C, so the current distribution reflects typical late-summer variability rather than an extreme signal. Updated model runs and local observations over the next 48 hours will narrow the range before resolution.