This chapter will introduce the UHI phenomena in Warsaw, in particular after a the defi nition of the pilot area, experimental microclimatic measurements were made in two housing estates, Koło and Włodarzewska, located at a similar distance from the city centre and from the city limits but different in terms of building periods and materials. A specifi c analysis of vegetation is provided to put in relationship UHI effects and allergenic factors. The case is completed by some solutions in terms of mitigation and adaptation to reduce urban warming impact. Keywords Microclimate • Urban spatial organization • Green areas • Mitigation Introduction -UHI as an Effect of Spatial Organization of the CityWarsaw is the largest city in Poland. Its area of almost 515 km 2 has signifi cant differentiation of land use. Currently about 248 km 2 is built-up area (48 %). Within this the greatest part (about 57 km 2 ) is covered by industry, trade units and transport systems. Forests make up about 15 % of the city. Urban parks and other recreational green areas cover 10 %. 12 % of the city territory is used as arable land, for crops and pasture. The category "heterogeneous agricultural areas" includes sparsely built areas and allotment gardens -11.3 % (Table 11.1 ). With 1.7 million residents and

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The study deals with an assessment and interpretation of the bioclimatic conditions in Vranje (southern Serbia). The study aims at temporal distributions of bioclimatic conditions focussing on extreme thermal stress based on the Universal Thermal Climate Index (UTCI). The meteorological data required for the calculation of UTCI concern hourly (7 and 14 CET) weather data collected for the period 2000-2017. The frequency of very strong heat stress (VSHS), very strong cold stress (VSCS) and extreme cold stress (ECS) for both morning and midday hours. Furthermore, the daily difference of the UTCI hourly values (diurnal UTCI change) are specified, giving the daily variance of heat and cold stress. The results revealed the frequency of days in which thermal stress prevails for the studied period. The obtained results show an increase in extreme heat biothermal conditions, while extreme cold biothermal conditions are in decline, especially in the last 10 years. However, the frequency (the number of days) of very strong heat stress (VSHS) increased since 2007. A spectacular increase in heat stress was observed in the month of September, particularly in 2015.