**Short-term forecast models from multiple sources converge on persistent cloud cover, northwest winds, and moderate rainfall or thunderstorms over Guangzhou on September 4, 2026, which should limit daytime heating and produce an overnight low near 23–24°C.** This aligns with the climatological average low of ~24.9°C for early September in the region while reflecting the influence of a passing weather system that enhances humidity and reduces radiational cooling overnight. High humidity (often 80–95%) and light-to-moderate winds further stabilize temperatures in the mid-20s, making extremes below 20°C or above 27°C less likely under current guidance. The closely matched market-implied probabilities on the tails (18°C or below and 28°C or higher both at 34.5%) versus the cluster around 23–26°C likely stem from residual model spread in precipitation timing and intensity, plus the short time horizon before resolution; updated runs from agencies such as the China Meteorological Administration or ECMWF/GFS ensembles in the next 24–48 hours could narrow this uncertainty. Historical analogs show that similar rainy patterns in early September rarely produce outliers beyond a few degrees of the consensus range.