**Forecast models for Busan indicate overnight lows near 17–18°C on October 17 under a migratory high-pressure system bringing partly cloudy skies, light northeast winds, and minimal precipitation.** Recent cooling after mid-month warmth has stabilized temperatures above seasonal averages, with daytime highs projected around 23–24°C, yet model spread and potential shifts in steering patterns sustain balanced trader positioning between sub-11°C and 21°C+ outcomes. Historical October minima in Busan cluster around 15–18°C, underscoring the current setup’s alignment with typical late-autumn variability rather than extremes. Official Korea Meteorological Administration updates and refined ensemble runs over the next 48 hours represent key catalysts that could narrow implied probabilities ahead of market resolution.