Forecast models for Zhengzhou on August 21 indicate scattered showers and thunderstorms tied to a west wind trough interacting with the western Pacific subtropical high, limiting solar insolation and capping the daily maximum near 30–31°C. High humidity (around 75–90%), light easterly winds, and persistent cloud cover further moderate peak temperatures by enhancing evaporative cooling and reducing surface heating. Official guidance from sources like the China Meteorological Administration and international ensembles (ECMWF, GFS) shows a narrow spread around these values, with rain probabilities of 40–70% during peak heating hours. This uncertainty between 30°C, 31°C, and 32°C+ outcomes stems from variable convective timing and intensity, which could either suppress or briefly allow higher readings depending on afternoon clearing. Historical August averages near 31°C provide context, but recent regional rainfall has increased soil moisture, slightly favoring lower maxima.