Short-range forecast models from agencies like the China Meteorological Administration show scattered afternoon thunderstorms and variable cloud cover as the main driver keeping highest temperatures in Guangzhou on August 4 clustered around 31–33°C. The East Asian summer monsoon supplies high humidity and moisture that fuels convective instability, limiting solar heating through reduced insolation while urban heat island effects in the Pearl River Delta sustain baseline warmth near seasonal norms of 32–34°C. Model spread arises from differences in predicted rainfall timing and wind patterns, with clearer skies favoring the upper end of the range and heavier showers capping it lower. Updated guidance expected within 48 hours could refine these probabilities as the event window approaches.