Climate changes, including changes in climate mean, variability and extremes, may affect both energy use and energy production. In particular, the increase of temperature and decrease of precipitation, projected for the 21st century over Mediterranean Basin, are likely to have adverse impacts on energy supply and demand. In our understanding of climatic change in the 21st century there are a number of fundamental uncertainties concerning external forcing changes, their influence on climate system, the effective climate change signal and the natural variability of climate system. To deal with these uncertainties, a set of high resolution climate change projection performer by state-of-art GCMs and RCMs in the frame work of the FP6 project ENSEMBLES were analyzed considering the period 1961-2050. Models with the best performances in describing climate over some areas critical for Italian electric system were selected, comparing simulated mean temperature and total precipitation simulated values with gridded data provided by ECA&D project. Using this runs subset, ensemble means have been calculated to investigate climate temporal and spatial variability over Southern Europe, with focus over Italy. Some scenarios describing the period 2011- 2040 have been elaborated with particular attention for the summer season in which climate change impacts are likely to be more serious because of the high temperatures impacts on peak energy demands. Despite the uncertainties due to the spread of the models, the increase in temperature of about 1°C projected for summer season of next decades highlights a serious vulnerability of energy sector.