SUMMARY
Abstract: This study aims to make a diagnostic analysis of seasonal and annual precipitation in different scales of time and relate them to atmospheric mechanisms that operate in different regions of the Maranhão State. For this we applied the methodology of Wavelet Transform (WT) the climatological series of rainfull in different homogeneous regions. The result of applying the WT to climatological series of rainfall has highlighted the different scales time, years that occurred heavy rains in the regions and show the dominant time scales and their interactions with smaller scales (seasonal, semiannual) and relate the variability of precipitation with major weather systems that operate in the state. Keywords: Rain, time series, time scale.