Recent short-term forecast uncertainty from Chinese meteorological models drives the tight clustering of market-implied odds around 23–27°C for Beijing’s September 26 high. Late-September climatology shows mean daily maxima near 24°C as the East Asian monsoon withdraws and cooler northerly flow strengthens, yet variable cloud cover and scattered rain—already evident in current runs—can suppress peak readings by 2–4°C through reduced insolation and evaporative cooling. Official guidance from the China Meteorological Administration highlights modest model spread in boundary-layer moisture and steering winds over the next 48 hours, keeping extremes below 20°C or above 29°C at very low implied probabilities consistent with historical September variability. Updated 24–48-hour model cycles and surface observations will likely refine the precise daily maximum before market resolution.