Review article

The article considers the main and alternative sources of data regarding precipitation.The author presents an analysis results of design rainfall characteristics in Saint Petersburg obtained at different times by different researchers in comparison with the data obtained by computer processing of the observation data covering the period 1897-1990. The analysis of discrepancies has identified two causes of errors: poor selection of regression equations and partial data processing. They were caused by the wish to simplify the data processing and further calculations; therefore they were obstacles one should avoid at updating the precipitation characteristics data.