The degradation of bathing conditions is a problem that has increased and generated international concern. Water from natural environments, when used for recreation, can bring a series of risks to those who come into contact, mainly because of the presence of pathogenic microorganisms in aquatic ecosystems. In Brazil, the National Environment Council regulated Resolution number 274 of 2000, which provides for bathing conditions. The main parameter to be investigated is the microbiota characteristic of domestic sewage, such as thermotolerant coliforms, Escherichia coli or enterococci. The possibility of influencing natural factors in modifying water quality in coastal regions is also highlighted. Therefore, the objective of this work is to evaluate, through statistical methods, the influence of natural factors on the bathing conditions of the beaches in the cities of Garopaba, Imbituba and Laguna -Santa Catarina, Brazil -from January 2010 to December 2019. Although factors such as the population increase, characteristic of summer, cause a great impact on water quality, factors such as the intensity of rain and variations in tides showed a significant influence on the bathing conditions of these beaches, as demonstrated by the statistical tests used in that study.