This study evaluated the performance of CMIP6 (Coupled Model Intercomparison Project Phase 6) climate models in simulating East Asian summer precipitation and projected its future changes using regional inter-monthly pattern metrics. CMIP6 models better captured observations with reduced biases compared to CMIP5 models. Future projections indicate an overall intensified monsoon band due to the increased moisture availability. The relative importance of atmospheric circulation and moisture change is identified for inter-model and scenario uncertainty, respectively.