Trends in Air Temperature and Precipitation in Southeastern Czech Republic, 1961-2020

This study presents a summary of sixty years of air temperature and precipitation measurements at the Žabčice weather station, located in the southeastern Czech Republic and operated by Mendel University in Brno. An instrumental dataset spanning two climatological normal periods (1961- 1990 and newly established 1991-2020) is analyzed for long term linear trends with monthly data presented in full span in Appendices. In the new climate normal period, the mean annual temperature increased from 9.3 °C to 10.3 °C with growing trend of 0.34 °C/10 years (p < 0.001). Every calendar month of year is warmer, with the highest and fastest increase in August (+2.0 °C, 0.64 °C/10 years, p < 0.001) and the lowest in October (+0.2 °C). Annual precipitation sum increased negligibly (+11.1 mm), however, the quarterly distribution significantly changes towards drier second quarter (-22.9 mm, p < 0.05) and wetter third quarter (+37.1 mm, p < 0.05). Number of tropical days (maximum daily air temperature > 30 °C) significantly increased (+4.44/10 years, p < 0.001), whereas number of frost days is negligibly decreasing (-0.88/10 years). Temperature derived Huglin index for vineyards increased by 369 °C to a seasonal sum 2062 °C (+84 °C/10 years, p < 0.001). This study provides evidence of the rate of changing climate at this southern Moravia lowland site. This study provided a summary and trend analysis of instrumental air temperature and precipitation dataset measured at Žabčice locality during the period 1961-2020, supplemented with selected agroclimatic indices. The dataset was utilized to establish a new climatological normal for the period 1991-2020 and both normal periods 1961-1990 and 1991-2020 were compared. We can conclude, that the mean air temperature is increasing on monthly, quarterly and yearly timescales. The fastest warming trend was observed during the growing season, peaking in June-August. There is an evident increase in extreme heat waves and other temperature-related indices, such as the Huglin index, suggesting a further rise in air temperature in the near future. Annual precipitation sums increased negligible, however, we can confirm a change in temporal distribution on an annual scale, in terms of decrease in the second quarter and increase in the third quarter. Supported by the Ministry of Education, Youth and Sports of the Czech Republic for the project SustES - Adaptation Strategies for the Sustainability of Ecosystem Services and Food Security in Adverse Natural Conditions, Project No. CZ.02.1.01/0.0/0.0/16_019/0000797, and by the National Agency for Agricultural Research, Ministry of Agriculture of the Czech Republic, Project No. QK1910338 "Early warning agrometeorological system for biotic and abiotic risks".