Extremely persistent flash heavy rainfalls (EPHRs) over the Sichuan Basin in China are influenced by both multiscale weather systems and complex underlying surfaces, making it difficult to understand the favorable dynamic mechanisms and to further improve operational numerical forecasting skills. In this study, EPHRs from 2010 to 2024 are objectively identified and then classified into three categories based on the SOM method. Precipitating characteristics for each category are further investigated from the perspective of the diurnal cycle and spatial features with the use of rain-gauge-based observations. Evaluations of the ERA5 reanalysis dataset, MSWX bias-corrected meteorological product, and CMORPH satellite-based precipitation product are performed to determine their capabilities in representing precipitating characteristics of different EPHR categories at different stages. The following results are obtained. During EPHR events, CMORPH outperforms MSWX and ERA5 in capturing heavy precipitation distribution, diurnal cycles, and evolution over the central basin. Both MSWX and ERA5 miss the central precipitation core, with MSWX showing premature peaks and ERA5 generating secondary evening peaks while overestimating precipitation duration. During events influenced by small-scale weather systems, all three products exhibit minimal false alarms but show the largest errors in intensity and diurnal variation. Under certain circulation types, MSWX and ERA5 significantly underestimate precipitation development with comparable metrics, while CMORPH achieves superior accuracy in precipitation intensity and correlations, yet it underestimates nighttime precipitation occurrences in steep western terrain. This study may help to facilitate not only theoretical studies but also numerical model developments for precipitation extremes.

Hourly precipitation data during the warm season (May to September) of 2011–2021 in Chongqing were used to analyze the diurnal variation characteristics. Results reveal a pronounced “night rain” phenomenon, with primary peaks from midnight to early morning and secondary peaks in late afternoon. These peaks and early-night troughs are generally consistent across annual and monthly changes, oscillating every 2–3 years, alternating between trough and peak years. Peak periods are May to June and September, while July to August are trough periods. Precipitation amount (PA), frequency (PF), and intensity (PI) peak phase generally delayed from west to east and south to north. Mountainous topography tends to moderate fluctuations in diurnal precipitation. Central and western regions mainly affected by synoptic systems, PA is mainly contributed by PF, and eastern regions influenced by terrain, PA is mainly contributed by PI. East-west propagation of precipitation is more prominent than north-south, with abnormally high in western, south of northeastern and Daba mountain area. Short-duration precipitation events occur approximately twice as frequently as persistent ones, yet persistent precipitation events dominate warm-season rainfall contributions, accounting for over 80% in most regions. Early-morning persistent rainfall prevails in western Chongqing, while afternoon short-duration precipitation events dominate both south of northeastern Chongqing and the Daba Mountains, corresponding precisely to the primary and secondary peaks of the diurnal variation curve. All persistent events exhibit strong asymmetry: the time from onset to peak rainfall is significantly shorter than the duration from peak to cessation. Mountainous terrain delays the peak timing of persistent rainfall, prolonging the pre-peak phase.