Purpose. The study aims at examining the main features of air temperature and relative humidity distribution in Ukraine to the middle of the 21st century and their changes relatively to the standard WMO climatic period 1961–1990 based on selected and verified regional climate model ensembles. The paper focuses on the analysis of the thermal and humidification regimes all for Ukraine as a whole, and for individual regions, administrative units and the Autonomous Republic of Crimea.

Methodology. In order to obtained long-term air temperature and relative humidity projections for the territory of Ukraine with high resolution, we used regional climate models (RCMs) from the EU FP-6 project ENSEMBLES (http://ensembles-eu. metoffice. com/) initiated with IPCC scenario SRES A1B. Multi-year monthly, cold and warm half-year and annual values of air temperature and relative humidity have been determined for the period 2021-2050 based on selected 10 RCMs ensemble for air temperature and 3 RCMs ensemble for relative humidity. Methodology of ensemble formation for air temperature projections is described previously in detail by authors. For relative humidity, according to the same methodology, three RCMs (REMO, RCA3, RACMO2) were selected that are part of the previous ensemble for air temperature and are the minimum number of models for the ensemble formation. The verification of the RCM’s outputs was performed for the standard WMO climatic period 1961–1990 using data observations from European database E-Obs (https://www. ecad. eu/) for temperature and data from Climate Cadastre of Ukraine (http://www. cgo. kiev. ua/index. php? dv= pos-klim-kadastr) for relative humidity.

Results. According to the obtained projections of air temperature to the middle of the 21st century, the monthly air temperature will increase in the range from 0.4 to 3.0 o C and the annual air temperature will increase in the range from 1.6 to 2.1 o C. Most intensive warming relative to the standard climatic period is expected in the northeast, east and south regions of Ukraine.