Traders have driven the market-implied probability for a 28°C high in Busan on September 22 to near-certainty because official Korea Meteorological Administration observations and model consensus show afternoon temperatures peaking at or just below that threshold under clear skies, light northeasterly flow, and high pressure. Daytime heating with dew points in the mid-teens and minimal cloud cover supports this outcome, consistent with late-September climatology for the region. The dominant positioning reflects real-time surface data and short-range forecasts from agencies like KMA, where traders betting real capital converge on the most likely maximum. A realistic challenge would require unexpected late-day marine-layer intrusion, stronger onshore winds, or rapid cloud build-up that caps readings a degree lower, though current conditions make such shifts improbable before resolution.