**Incoming rainfall combined with northerly cold air advection is the main driver of cooling and uncertainty in Chongqing’s overnight minimum on August 29.** Official forecasts from the Chongqing Meteorological Bureau and international models indicate a strong rain event beginning late on the 28th and continuing through the 29th, with widespread showers, thunderstorms, and locally heavy downpours (30–80 mm, isolated higher amounts) accompanied by gusty winds. This pattern has already lowered daytime highs from recent 37–40 °C readings and is expected to keep skies cloudy overnight, limiting radiative cooling while delivering additional evaporative and advective cooling. Resulting minimum-temperature guidance clusters around 22–24 °C for the early-morning hours, with some runs showing 21 °C or lower if heavier rain persists and others holding near 25 °C if cloud cover or timing shifts. The tight clustering of market-implied probabilities across 21–25 °C directly reflects this narrow but still uncertain range produced by differing model solutions for rain timing, intensity, and the precise strength of the cold-air push. Historical late-August minima in the city are typically higher (around 26 °C), underscoring how the current synoptic setup is the dominant near-term factor.