**Current forecasts from multiple meteorological sources indicate a minimum temperature for Guangzhou on September 21 likely falling in the mid-20s °C, aligning with the closely matched market-implied probabilities around 24–26 °C.** High humidity levels near 80–95% overnight, combined with partly cloudy skies and a chance of showers or thunderstorms, are expected to limit radiative cooling and keep the low from dropping sharply below recent norms. Model outputs, including detailed hourly runs, show early-morning readings stabilizing near 24–27 °C after daytime highs of 32–35 °C, consistent with late-summer subtropical conditions where weak steering winds and persistent moisture moderate temperature swings. Traders appear focused on the narrow band of outcomes because small shifts in cloud cover timing or localized precipitation could easily move the exact minimum across the 24–26 °C thresholds, while lower probabilities on 23 °C or below reflect the limited cooling potential under these conditions. Updated model runs and overnight observations ahead of the 24-hour resolution window will be the key variables.