Recent forecasts from multiple models indicate a likely overnight low near 20–21°C in Busan on September 10 under persistent northeasterly flow and partly cloudy skies, consistent with the market’s leading outcomes clustered around 18–20°C. Stable high pressure and moderate humidity are limiting radiative cooling, while light winds reduce mixing and allow modest temperature drops after sunset. Traders appear to weigh these conditions against typical early-September maritime moderation in the region, where historical lows often fall in the 19–22°C range absent stronger frontal systems. Minor model differences in cloud cover and boundary-layer moisture create the tight spread across 18–21°C probabilities, with resolution hinging on official Korea Meteorological Administration observations at the close of the 24-hour period.