This diploma thesis covers the spatial processing of weather data and focuses on the analysis of the radar image of precipitation, which is available on an open access website of Slovenian Environment Agency (Agencija Republike Slovenije za okolje or ARSO). The thesis is divided into two parts, theoretical and analytical. Theoretical part describes the functioning of the weather radar, the way of collecting data, and history and future of radar measuring of rainfall in Slovenia. The focus of the central topic is the radar image of precipitation, its technical characteristics, such as range and display time of the radar, and the examination of the connection between the parameters of radar reflectivity (Z) and rainfall depth. In the analytical part, FME Desktop tool is used to obtain radar images of precipitation from the website of Slovenian Environment Agency (ARSO), then the images are georeferenced, edited, and reclassified. The aggregation and calculation of normalized sums follow the data collection and processing. The results obtained are analysed and displayed on maps using the QGIS software tool. The thesis studies the spatial distribution of rainfall and discusses whether rainfall intensity can be directly linked to rainfall depth. The collected numerical results were used to present the connection between the two parameters mathematically and practically.