Abstract: To study the cloud-seeding effects during the opening ceremony of the Nanjing 2014 Youth Olympics Games, a silver iodide cloud-seeding parameterization was implemented to the Thompson microphysics scheme of the Weather Research and Forecast (WRF) model. The results revealed that surface precipitation was decreased due to seeding, and the subcloud dry layer played a key role in modifying seeding effects. Furthermore, a low relative-humidity environment was favorable for rain suppression by cloud seeding; however, under a high relative-humidity environment, the opposite effect was observed. Cloud seeding enhanced the formation of snow, but weakened its growth, specifically deposition growth. Thus, the concentration of snow increased, but its size decreased. The snow melted and turned into a large number of small raindrops, which evaporated easily; hence, the precipitation on the ground was less.