EMS Annual Meeting Abstracts Vol. 15, EMS2018-172, 2018 © Author(s) 2018. CC Attribution 4.0 License. Thunderstorm days during periods with hot and heat weather in Warsaw, Budapest and Naples Katarzyna Grabowska (1) and Joanna Popławska (2) (1) University of Warsaw, Faculty of Geography and Regional Studies, Department of Climatology, Warsaw, Poland ([email protected]), (2) University of Warsaw, Faculty of Geography and Regional Studies, Department of Climatology, Warsaw, Poland ([email protected]) Many climatologists have drawn attention to the increasingly frequent occurrence of hot and heat days and nights, tropical days, and especially heat waves in Europe. It seems that the incentives will be even stronger weather if, in these days there are also thunderstorms. The tourists trips 1 or 2 weekly, connected with change of climate zone, especially in the warm half, are not good for us because of the short period of acclimatization. Popular with tourists is the Mediterranean Sea Basin at the same time an area of high thunderstorm activity. Among the many localities, is Naples has a very large number of thunderstorms (average of 37.8 thunderstorm days of the year). Also visited by tourists city of Budapest (an average of 26.5 thunderstorm days of the year) and Warsaw (average 26.9 thunderstorm days of the year) located in the cooler warm temperate, are subject to hot and heat weather, during which there are thunderstorms. The aim of the study is to determine the frequency of thunderstorm days during the hot and heat days and nights in Warsaw, Budapest and Naples in the years 1986-2015. Data on the number of thunderstorm days and daily values of maximum and minimum air temperatures are de- rived from archival database OGIMET and TUTIEMPO, and analysis of synoptic situation and vertical aerological sounding. Heat and hot weather is characterized by the corresponding ranges of values of maximum and minimum tempera- tures. The hot weather represent: hot day, warm night and very warm night. The heat weather represent: heat day, very heat day, super heat day and hot night and very hot night. The most difficult thermal conditions prevail during the tropical day. In determining the days and nights of hot, heat and tropical days in Naples (transitional subtropical climate) used a classification of the selected thermal characteristic days expanded with respect to Warsaw and Budapest (transi- tional warm temperate climate) with a super heat days (Tmax > 37oC) and very hot nights (Tmin > 23oC). Thunderstorms in all cities popping up throughout the year. In Naples, usually in autumn, when it is still warm and the humidity is higher than in summer. For this reason (high maximum, minimum air temperature and less humid) thunderstorms occur less frequently during hot and heat weather – a 25% and even 17% of the total thunderstorms. In Warsaw and Budapest, most thunderstorms occur in summer, which is more humid than in Naples. In Warsaw and Budapest in the summer there is more frontal thunderstorms. The thunderstorms were relatively rare in the days under consideration of the thermal characteristics. The greatest chance of popping up during the warm and very warm nights and hot days..