This master study addresses the monthly evolution from April to September of the extremeheat wave that occurred in Europe in 2018. Heat waves cause serious hazards related to regionaleconomics, ecosystems, human health and deaths. According to the large number of studiesexisting on heat waves, most climate models predict that in the future, heat waves will appearmore often, last longer and increase in magnitude. Heat waves therefore require urgent attentionand enhanced understanding of the processes behind this phenomenon is thus the motivationbehind this thesis. The thesis will investigate how 1) atmospheric blocking was associated with alarge-scale quasi-stationary mid-latitude flow regime and 2) soil moisture-temperature feedbackcould explain the anomalously high temperatures. To analyze these mechanisms and to seehow they co-interact, a high resolution reanalysis dataset has been applied in order to provide acomplete and consistent dataset. The main finding is that the strongest and most prolonged heatwaves could mainly be identified in Northern Europe. In May, a strong heat wave which lastedbetween 12 to 36 days with a monthly mean temperature anomaly peak of approximately 6◦Ccould be identified in Southern Norway and Sweden. The exceptional temperatures could beexplained from the high amount of days with a Scandinavian blocking regime which blocked theusual west to east traveling cyclones. As a result of the high frequency of atmospheric blocking,anomalously high positive downward radiative fluxes were identified over Southern Norway andSweden which heated the surface and increased the latent heat flux, which contributed to soildrying and soil moisture was not found to control the latent heat flux. In June, the blockingfrom May was absent over Scandinavia, but a strong heat wave lasting for approximately 9 to24 days over the British Isles was placed below an atmospheric blocking regime which couldpartly explain the prolonged heat wave. Nevertheless, the temperature anomalies were weakwith a monthly mean temperature peak of approximately 3◦C. However, the soil moisturecontinued to decrease in Northern Europe which started to limit the latent heat flux and asignificant soil moisture-temperature coupling could be recognized in Southern Sweden and asmall part of Eastern Norway, but due to the absence of high pressure anomalies the dailymean temperature anomalies were quite weak. In July, a strong and long lasting heat waveagain returned over Southern Norway and Sweden which lasted between 15-24 days with amonthly mean temperature peak of approximately 5◦C. The anomalously temperatures couldbe explained from an interlinkage between high anomalously frequency of Scandiavian blockingand soil moisture-temperature feedback which was reflected in the exceptional high negativelatent heat flux anomalies of approximately−20Wm2and positive sensible heat flux anomalies ofapproximately+40Wm2.