Abstract: Due to the rugged terrain, heavy precipitation in the Nanling Mountains exhibits localized and sudden features, which are intensified by its complex topography and geographical locations. The short-duration heavy rainfall during the flood season poses significant threats to local socio-economic activities and public safety. Hourly precipitation data from automatic meteorological stations and ERA5 reanalysis data from 2013 to 2022 were analyzed to divide the flood season into four sub-seasons, including late spring (April), early summer (May to June), midsummer (July to August), and early autumn (September). Then, the spatiotemporal characteristics of short-duration heavy precipitation during the flood season in the Nanling area and the effects of topography were investigated. The results are as follows. (1) Short-duration heavy rainfall exhibits a distinct spatial pattern in the Nanling region, showing more frequent occurrence on the southern slopes than the northern slopes, and more frequent on the eastern and western sides than the central part. It is mainly concentrated on four regions, the southern slopes of Yuechengling, Dupangling, the southwestern of Qitianling, and eastern and southern Wanyangshan, with average precipitation frequencies of 89.1, 64.7, 49, and 52 times (station·10a)⁻¹, respectively. The average precipitation intensity of short-duration heavy rainfall shows minimal spatial variation, and precipitation amount is consistent with that of precipitation frequency patterns. (2) Seasonal variability is pronounced for short-duration heavy rainfall, increasing from late spring (5.3 times (station·10 a)⁻¹) to early summer (12.6 times (station·10 a)⁻¹). A particular increase is found on the southern sides of Yuechengling, from 11.1 to 23 times (station·10 a)⁻¹. In midsummer and early autumn, the frequency decreases to 8.6 and 3.7 times (station·10 a)⁻¹, respectively. (3) Diurnal peaks occur in the early morning (03:00—06:00) and afternoon (15:00—19:00) in the Nanling Mountains, while the peak mainly occurs from midnight to early morning in late spring. In early summer, early-morning peaks are found on the southern Yuechengling and Dupangling, while peak shifts to afternoon and evening on the southern Qitianling and eastern and southern sides of Wanyangshan. In midsummer, short-duration heavy rainfall mainly occurs in the afternoon except for the southern side of Yuechengling. In early autumn, short-duration heavy rainfall decreases in all regions, while the afternoon peak remains on the southern Qitianling and the eastern and southern sides of Wanyangshan. (4) Seasonal transition from spring to summer and autumn correlates with decreasing amount and coverage of short-duration heavy rainfall in the morning, but increasing afternoon events with the expansion from east to west. This is linked to the seasonal northward shift of circulation and east-west solar radiation gradients. (5) Morning short-duration heavy rainfall frequently appears in the western Nanling, which is possibly driven by enhanced southwesterly flows and orographic lifting. But afternoon short-duration heavy rainfall is more common in the eastern Nanling, possibly resulting from solar heating-induced thermal instability.