To know the weather from year to year is of great value to a proper agricultural planning. The study was conducted in the State of Pernambuco, with data basis of temperature and rainfall of at least 20 years of observations of 45 meteorological stations. The function of density probability of the incomplete gamma distribution was used to evaluate the occurrence of dry, normal and rainy years. The monthly climatic water balance was estimated by the method proposed by Thornthwaite and Mather (1955) and interpolation of data for the plot was made using the Kriging method. The results indicated that the highest rainfall occurred in the Zone da Mata in the south of the State with around 2800 mm year-1. The water excess presented its highest levels in the Zona da Mata mesoregion with availability of nearly 1200 mm year-1 for the rainy years and water deficit was higher in the Sertão Mesoregion of Sertão of San Francisco reaching 1000 mm year-1, being required full irrigation for the crops.