The aim of this study was to check if there is any relationship between mortality due to circulatory diseases, according to sex, and the climatic variability in the region of Aveiro. The spectral analysis and the methods of correlation allow the identification of the associations between the data on monthly mortality and the monthly climatic variables between 1990 and 2000. This study also proposes a statistical model, which is based on the oscillations identified by the spectral analysis, to represent the variability of mortality. A strong coherence is shown between the climatic variables and mortality, especially in minimum temperature, in the peaks of 3 and 12 months. - All the diseases show the peak of 3 months, being however more distinct in men than in women. The model applies to the prediction for the following months of the number of incidence of deaths caused by cardiovascular diseases.