Scenario-Dependent Future Trends of Consecutive Dry Days From July to September: A Case Study for Hungary

The maximum number of consecutive dry days using the threshold of 3 mm (CDD3) of daily precipitation is analysed for Hungary from July to September for the period 2004–2100. Summer is the wettest season in Hungary and has a key role in the growing processes of plants; therefore, the projected increase of potential drought conditions in these months is highly important. One of the novelties of the present study is analysing CDD3, which represents extreme drought well and has the advantage of being calculated from daily precipitation. The HuClim dataset is used for investigating the past (i.e., 1971–2023), while for the future (2041–2100) the multi-model mean of six regional climate model simulations is analysed, taking into account three different RCP scenarios (RCP2.6, RCP4.5 and RCP8.5). In order to eliminate the systematic errors of climate model simulations, a simple bias-correction was applied to the calculated index. According to our results, the average value of CDD3 was 21 days in 2004–2023, and by 2081–2100 it can exceed 25 days if the RCP8.5 scenario is taken into account. Moderate long CDD3 is likely to occur less frequently, but extreme long CDD3 is projected to occur in more than 4 years within a 20-year-long period by the end of the 21st century in the central parts of Hungary, in the case of RCP8.5. The RCP2.6 scenario does not show substantial changes compared to the present conditions, while in the case of RCP4.5 the greatest drying trend is simulated for the period 2061–2080. Overall, more frequent and more intense drought periods are projected for the next decades in the case of RCP4.5 and RCP8.5. This may induce adverse effects on agriculture (e.g., yield loss), which highlights the importance of adaptation strategies, as food security is a key issue.