Abstract: Based on the qualified hourly precipitation data of 74 national meteorological stations in Hubei province from June to August during 1983—2017, the spatio-temporal distribution characteristics of hourly heavy rainfall during summer were investigated. The results showed that the annal variation and diurnal variation of frequency during summer were nearly identical to the thresholds above 20, 30, 50 mm per hourly. The diurnal variation of heavy rainfall frequency was the characteristics of double-peak structure, which happened on 17：00—20：00 and 8：00,respectively, the continuous peak value during the evening formed a sustained active heavy rainfall period. The hourly heavy rainfall mostly occurred in the eastern part of Hubei province. With the increase of hourly heavy rainfall intensity, the high-frequency stations expanded to the west. The mesoscale convergence line or vortex on the ground under special topographic conditions was an important factor that caused the maximum frequency stations of hourly heavy rainfall. The diurnal variation of heavy rainfall frequency events with different durations showed that the high-occurrence period of short-duration heavy rainfall events was from afternoon to evening, which contained many local short duration heavy rainfall events, while the long duration heavy rainfall events were nocturnal, corresponding to the systematic heavy rainall process. There were three main oscillation modes of quasi-12 years, quasi-6 years and quasi-2 years for short duration, and one main oscillation mode of quasi-6 years for long duration. The high frequency stations of long duration heavy rainfall events were mostly concentrated in eastern Hubei, which was related to the development direction of southwest low-level jet stream in summer, while the short duration distribution was more extensive, which was related to the formation variety of local short-duration heavy rainfall in summer. The distribution of maximum frequency stations was closely related to the horseshoe topography of Hubei province, and most of them were located in the mountainous areas on the east, west and north sides of Hubei province.

Key words: hourly heavy rainfall, frequency, duration, terrain, Hubei province