Given the necessity to have the biggest knowledge in the behavior of the atmospheric discharges in the Medellin city and near municipalities, and taking advantage of the data gathered by Lightning Location System (LLS) property of EPM E.S.P. (Energy Distribution Company), a study was made that characterizes the behavior of the atmospheric discharges in El Valle de Aburrá. The analyzed data were collected between years 1995 - 2004. The data were statistically processed obtaining to characterize in space and time the major parameters of atmospheric discharges, such as; polarity, multiplicity, magnitude, ground flash density (GFD), Keraunic level (Stormy days) and fuzzy ground flash density (FGFD). The FGFD consists of the evaluation of the GFD of a certain space using the Fuzzy Methodology. The analysis of the information allowed validate the use of formulate proposed by the international literature, determining if it is been worth or not to use them in the region under study. Additionally it is evaluated the validity and utility of the use of the FGFD.