Widespread cloud cover and heavy rainfall expected across Guangzhou on August 31 are the main factors capping maximum temperatures near 30–32 °C in the latest model guidance. Persistent monsoon moisture and northeast flow favor widespread thunderstorms that reduce solar insolation and promote evaporative cooling, keeping surface highs below the 33 °C climatological average. This scientific setup explains the tight clustering of market-implied probabilities around 31–34 °C, where small differences in convective timing or brief cloud breaks could shift the daily peak by 1–2 °C. Traders appear to weigh the high likelihood of suppressed heating against residual uncertainty in exact rainfall timing. Updated runs from the China Meteorological Administration and global ensembles will provide the next key data points before resolution.