Summary:

The aim of the study was to analyze and evaluate the occurrence of atmospheric drought during summer half-year in Wroclaw - Swojec over the 50 years 1961÷2010. For that purpose daily values of precipitation totals were used, measured at the Agro- and Hydrometeorology Observatory that belongs to the Wrocław University of Environmental and Life Sciences. Analyses were performed for particular months from May to October for 50-year period 1961÷2010. The assessment of atmospheric drought occurrence was based on the string of days without precipitation, using the criterion proposed by Schmuck for their designation. The analyzes carried out showed a decreasing tendency of the number of strings of days without precipitation lasting 9 days and more during the 50-year period 1961÷2010, but not statistically significant. This trend has stabilized during a 30-year period 1961÷1990. Mostly drought occurred in October and the least frequently in July. Longer periods without precipitation (moderate drought ) were characterized by more frequent occurrence in late summer (August ) and in September and October. In contrast, intensive drought on that area occurred sporadically and only in the period of September - October. The obtained results were consistent with the results of other authors obtained for Wroclaw for different many - year periods.