Recent numerical weather prediction ensembles from sources including the Korea Meteorological Administration and global models indicate afternoon highs in Busan on September 13 clustering near 28–29°C under stable high pressure, with light southerly winds and partly cloudy skies. This setup supports the market’s tight clustering of implied probabilities around 30–31°C, as modest variations in insolation from cloud timing and boundary-layer mixing can shift the daily maximum by 1–2°C. Historical September baselines for the region average near 27°C, but current dry conditions and weak sea-breeze development raise the potential for brief spikes above 30°C before any evening cooling. Updated model runs and local observations over the next 48 hours will refine these thresholds ahead of market resolution.