Rainfall is one of the main meteorological factors responsible for agricultural crops yield. Its irregularity observed more intensely in the Northeast causes the alternation of annual agricultural production. Thus, this study aimed to determine the characteristics of the wet and growing season based on daily rainfall data between 1973 and 2008 in Rio Largo, Alagoas. The beginning (potencial and success), ending and length of the cultivation and rainy season were determinate by direct methods using daily rainfall and reference evapotranspiration. Statistical analysis of cultivation and rainy season characteristics were done using the Instat Climatic software. The expected rainy season, at 80% probability, began on April 7th and finished on October 24th, with a duration of 221 days. The beginning of the rainy season was anticipated in La Niña years (ten days) and postponed in years of El Niño (nine days) and consequently, cause a decrease in the cultivation length season for El Niño years and increase in La Niña years.
rainfall; rainy season; ENSO
