During the early summer of 2022, the average rainfall in northeastern China (NEC) was 144.9 mm, which exceeded that in historical records by 62%. The average rainfall in the region is 89.5 mm. This information was obtained from an assessment of summertime rainfall in the NEC region using the sixth Coupled Model Intercomparison Project (CMIP6) model based on precipitation data from CN05.1. The model that performs best in replicating the climatological spatial distribution and interannual variability in precipitation is considered optimal. It has been found that a multimodel ensemble performs better than a single model simulation. The three most favorable models, namely, EC-Earth3-Veg, EC-Earth3, and MPI-ESM1-2-LR, can potentially form the optimal model ensemble, also known as the HMME. Compared with a single model and an ensemble of all 20 models, the HMME reduces the wet bias on the southeastern side of the Da Xing-An Ling Mountains. Additionally, the HMME predicts a steady increase in daily precipitation in the NEC region from 2015 to 2100, with precipitation rates increasing by 0.05 mm/10a and 0.15 mm/10a for the SSP245 and SSP585 scenarios, respectively. By the end of the 21st century, the entire region experienced a significant increase in precipitation, despite differences in precipitation patterns between scenarios at different times of the year. The largest increase is witnessed in the southern region of northeastern China.