Forecast models from sources including the China Meteorological Administration indicate Chongqing's overnight minimum on September 12 will settle near 21°C, supported by light northwest winds, moderate humidity around 65-80%, and partly cloudy conditions limiting strong radiative cooling. This aligns with typical early-September climatology, where average lows range 20-23°C absent major cold-air intrusions or heavy rain. Recent model runs show minimal spread, with no significant frontal passages expected to drive sharper drops toward 17°C or below. Traders appear to weigh these stable atmospheric patterns and real-time station observations heavily, producing the elevated implied probability for 21°C while assigning moderate odds to nearby values amid minor forecast uncertainty.