Geographia Polonica 2021, Volume 94, Issue 2, pp. 267-282 https://doi.org/10.7163/GPol.0205 INSTITUTE OF GEOGRAPHY AND SPATIAL ORGANIZATION POLISH ACADEMY OF SCIENCES www.igipz.pan.pl www.geographiapolonica.pl TOURISM CLIMATE CONDITIONS IN THE WESTERN SUDETES (POLAND) IN RELATION TO UTCI Bartłomiej Miszuk Institute of Meteorology and Water Management National Research Institute ul. Parkowa 30, 51-616 Wrocław: Poland e-mail: Bartlomiej.Miszuk@imgw.pl Abstract The region of Western Sudetes is one of the most popular tourist areas in Poland. Simultaneously, it is also characterized by significant variability in terms of climate conditions. Therefore, the main goal of the analysis was to evaluate variability in heat stress frequency according to UTCI and examine how it corresponds to the results of the tourism-climate index (WSI). The results for both indices, for 1971-2015 data, showed significant differences between the summit and the lower located mountain zones. Analysis on multiannual trends of UTCI classes showed significant increase in the frequency of thermoneutral conditions and decreasing tendency for cold stress categories. Key words bioclimate  Sudetes  UTCI  WSI Introduction The Western Sudetes are one of the most out- standing regions of Poland in terms of climate conditions. They are located in the south-west Poland (Lower Silesia) and include the Giant Mts. and Isera Mts. Such a location makes them exposed to frequent advection of polar air masses from the Atlantic Ocean. Conse- quently, it results in specific precipitation and fog conditions that are significantly different from other regions of Poland. In terms of the influence of weather on human organism, the most crucial aspect is related to very high wind speed, noticed especially in the sum- mit zone of the mountains. Analysis focused on wind conditions of the discussed region showed that the highest parts of the Giant Mts. is one of the most windy regions in whole Europe (Błaś & Sobik, 2005). Mean annual wind speed on Śnieżka reaches 12.7 m·s -1 (Otop & Miszuk, 2011; Błażejczyk, 2019), significantly exceeding values noticed in the surrounding areas. In terms of thermal condi- tions, mean air temperature in the Western Sudetes varies from about 7.5°C in their low- er parts to 0.8°C on Śnieżka Mtn. It should be also emphasized that over 300 foggy days