**Warm, moist southerly flow ahead of an approaching upper-level trough is the dominant driver keeping overnight lows elevated in Busan.** Current model guidance from multiple sources shows minimum temperatures on October 10 likely in the 19–21 °C range under mostly cloudy skies and scattered showers, well above the long-term early-October average of roughly 15 °C. This pattern reduces radiative cooling and aligns with the market’s elevated implied probability for 23 °C or higher while supporting the cluster of outcomes in the mid-to-upper teens through low 20s. Historical October lows in Busan rarely exceed 20 °C without such advection, and the absence of northerly cold-air outbreaks in the latest extended outlooks reinforces trader consensus around milder readings. Updated Korea Meteorological Administration forecasts and next model runs will provide the next key data points for resolution.