**Recent northerly wind shifts and associated cold air advection are the primary drivers tightening trader focus on a 15–16°C minimum for Qingdao on September 30.** Official model guidance shows a transition from southerly flow to stronger northwest winds, promoting clearer skies and enhanced radiative cooling after daytime highs near 24–25°C. This setup typically yields overnight lows in the mid-teens Celsius, consistent with climatological September minima around 18°C but tempered by the fresh air mass. Minor model disagreements on exact cloud cover, wind mixing, and timing of the coldest hour create the near-even split between 15°C and 16°C implied probabilities, with lower outcomes like 14°C remaining competitive if cooling strengthens. No major data releases are scheduled before resolution, leaving final surface observations to determine the precise minimum.