Abstract: The present thesis examined changes in the annual and seasonal distribution of daily maximum and minimum temperatures for northeastern Spain. A better understanding of the ongoing changes in the temperature means and extremes was the primary objective. Further aims involved the analysis of large-scale atmospheric circulation patterns at different geopotential levels as well as the Mean Sea Level (MSL) pressure based on climate composites analysis and canonical variates in order to quantify the driving forces beyond the observed variability. Finally, this work aimed to assess future climate projections of seasonal temperature and their spatial variations to improve the understanding and prediction of the long-term trends of temperature means and extremes simulations. To achieve all these goals, it was necessary to develop a homogenous dataset with high spatial and temporal resolution. The next few paragraphs answer the main research questions raised during this work.