Galactic cosmic rays (GCRs) are among the possible mediators of the solar influence on climate and weather. However, the impacts of GCR-induced ions on cloud formation and climate systems are not fully understood. In this paper, we show that the high-altitude clouds around the tropical regions associated with deep convective activities are susceptive to the decadal cycle of GCRs and that their impact and responding areas are seasonally variable. The most notable responses were found in August over land areas, suggesting that the susceptivity of clouds to GCRs may be dependent on the depth of convective activities and the abundance of aerosol precursor materials. We suggest that the positive feedback mechanism may be strengthening the GCR–cloud connection, maximizing the impact of GCR cycles with a lag of 1 year.