As is well-known, the river stream-flow as the main source of water resources, is formed and changed under the influence of climate conditions and physiographic characteristics of watershed basins. Snow storage, liquid precipitation in the period of snow-melt flood, degree of moisture of the area, etc. are the main hydro-climatic factors determining the amount of the annual river flow. On the territory under consideration, in this case the region of the North of the Russian Plain is selected as which, flow fluctuations are well-defined as a result of changes in space and time of the main forming it factors and, mainly, the meteorological factor. In this regard, the main objective of the work is to find the connection between rainfall and river flow, as well as to identify patterns of spatial and temporal changes of river flow and precipitation. During the study, the authors identified the dependencies between precipitation and the layer of the run-off in hydrological seasons. In particular, the closest connection was established between precipitation and the flow of summer-autumn period, where the correlation coefficient (r) for posts of 8, reaching r = 0, October, except August (precipitation) and April (run-off), where these periods did not coincide.