Abstract: This paper provides a comprehensive evaluation of the performance of CMA-MESO (China Meteorological Administration Mesoscale) model, a precipitation forecasting system, in predicting summer rainfall patterns in the Sichuan Basin and surrounding areas. The study is based on 12–36 h hourly precipitation forecast data obtained from CMA-MESO, starting at 0800 BJT (Beijing time), and hourly gauge–satellite–radar merged precipitation products. These data were collected during the summer months (June–August) of 2020. The findings reveal that CMA-MESO successfully captures the spatial distribution characteristics of summer precipitation. Observations show that higher mean hourly precipitation amounts and frequency values are primarily found in the high-altitude mountains to the west, north, and east of the Sichuan Basin. Similarly, higher precipitation intensities are mainly located on the windward slopes of these mountains. However, the forecasted centers of precipitation amount and frequency are located to the south of the observed locations. CMA-MESO reasonably reproduces the diurnal variation of mean summer precipitation. This includes the eastward-delayed diurnal peak phase of precipitation amount and frequency in the study region, the bimodal pattern with a morning peak and an evening subpeak of regional average precipitation amount and frequency, and a single diurnal peak of regional mean precipitation intensity. However, the diurnal variation phase in the forecast precedes that of the observations. Furthermore, the forecasted hourly precipitation amount is larger than the observed values. Notable positive deviations mostly occur at night (2100 BJT–0300 BJT) and from afternoon to evening (1400 BJT–2000 BJT). The nocturnal deviations are mainly contributed by forecast deviations of general rainfall (0.1–10 mm h⁻¹) and the major parts were observed from the southeastern margin of the Qinghai–Xizang Plateau to the western Sichuan Basin. The afternoon deviations are mainly contributed by forecast deviations of heavy rainfall (≥10 mm h⁻¹) and mainly locate in the east and south of the Sichuan Basin. The forecasted deviations can be attributed to a combination of thermal and dynamic fields along with the influence of topography on rainfall.