Recent forecasts from global and regional models indicate a high of 26–28°C in Busan on September 30 under mostly clear to partly cloudy skies and light southwesterly winds, positioning 27–28°C as the most probable outcomes. Seasonal cooling from peak summer values, combined with reduced cloud cover that enhances daytime solar heating, supports this range while limiting extremes. Historical late-September averages near 24–26°C provide context, with current high-pressure dominance reducing precipitation chances and allowing modest warming above climatology. Minor model spread on exact peak timing and boundary-layer mixing introduces the observed uncertainty reflected in market-implied odds, with fresh observational data from the Korea Meteorological Administration expected to refine guidance before resolution.