【摘要】：This paper investigates the diurnal variations of summer precipitation in Shanghai by using the city's hourly precipitation data over a span of 35 years. The result shows that the precipitation peaks twice, i.e., in the morning and in the afternoon. Precipitation in the morning is characterized by light to moderate rain, and that in the afternoon by heavy to super heavy rain. The peak of short-duration precipitation is mostly found in the afternoon and at dusk, and that of long-duration precipitation in the morning. Most of the precipitation events in Shanghai are of a short duration of2-3 hours. Basically, the precipitation is spatially distributed in three areas: the eastern coastal and central urban area,where the precipitation peaks mostly in the afternoon, the southern coastal area, where the precipitation peaks both in the afternoon and during the night, and the western area, where long-duration precipitation accounts for a much larger proportion than the other two areas.