Water availability is fundamental for human health, ecosystem function, economic activities. Future climate change scenarios about temperature and precipitation in the next decades over Italy have been elaborated using an analysis system in which observation data from the international data-sets (ERA40 and E-OBS) have been used together with regional model outputs developed in the framework of European Project ENSEMBLES. The analysis process used ensemble means to reduce the uncertainty present in each model and to give a variability range in the projections: scenarios have been elaborated using the ENSEMBLES models with the best performances in the description of past century climate characteristics over Italian Region. Thanks to high spatial resolution of regional models (25 km), it was possible to estimate climate changes over limited area (as Alpine Region or Po Basin), that are particular important for water resources, as well as to characterize meaningful climate changes over the whole Italy. The warming trend of the last decades is discernible in local measurements and satisfactory described by state-of-art-models and a significant increasing of temperature is projected for the next decades. Instead changes in precipitation patterns are complex and of difficult interpretation. Then the more frequent circulation regimes have been studied using EOF and cluster analysis and the link between the pressure regimes and the corresponding temperature and precipitation fields have been investigated over Italian Region.