Greece is located over a prone region regarding the climate change. The aim of this study is to investigate the projection of cloud cover fraction and surface relative humidity during the period from 1970 to 2099. In this analysis we use six high-resolution regional climate model simulations (RCMs) available from the EURO-CORDEX program. The RCMs include the historical period from 1970 to 2005 and the future period from 2006 to 2099 under the influence of the representative concentration pathways (rcp) rcp2.6, rcp4.5 and rcp8.5. Results show significant projected changes mainly during the last period of 21st century according to the rcp8.5 scenario. In particular, during the 2070-2099 period, with respect to a reference period (1976-2005), both the cloud cover fraction and the surface relative humidity are reduced about 5% and 4% - 8% respectively, over the continental Greece. Focusing on the winter season, the comparison between future and reference periods shows that cloud cover fraction presents a significant relative decrease about 10 % to 20% mainly during the last period of 21st century. Finally, surface relative humidity during 2070-2099 shows insignificant changes according low and moderate scenarios (rcp2.6 and 4.5) , and limited changes for the high emission scenario (rcp8.5).