Heat wave of August 2012 in the Czech Republic: comparison of two approaches to assess high temperature event

We present an analysis of a period of high air temperature that occurred in the second half of August 2012 in the Czech Republic (CZ). We use and compare the results of two different approaches for the evaluation of high air temperature events. The Weather Extremity Index (WEI) evaluates the extremity and spatial extent of the meteorological event of interest. The second method is based on the duration of daily maximum air temperature above specific thresholds. In 2012, the high air temperature in the CZ lasted from 18 August to 24 August (18/8 to 24/8). It was connected with the inflow of hot air from northern Africa between the low pressure trough over the eastern Atlantic and the region of high pressure in central Europe. The high air temperature culminated on 20/8 when its maximum was greater than 30°C across the whole of the CZ. The highest daily maximum air temperature on record in the CZ with a value of 40.4°C was observed at the Dobřichovice station. Our results demonstrate that the studied period was quite extraordinary, occurring so late in the summer with a relatively large areal extent and extremity of detected maximum air temperature. Furthermore, the WEI was found useful for identification of very extreme high air temperature events and facilitated intercomparison in terms of extremity and spatial extent. However, WEI cannot be used for detection of periods with a persistent relatively high air temperature that could have severe impacts on both human activities and natural ecosystems but during which the extremity of observed air temperature values is not very high.