In this work, the atmospheric corrosivity of a low carbon steel A-36 is assessed after exposure to the environment of Panama City (Main Campus of the University of Panama). Seasonal effect was determined by exposing, both, during dry and rainy season. The levels of contaminants (Cl- y SO2) observed during this study were lower than those obtained in previous studies (MICAT-Panama). The extrapolated corrosion values were 13 ??m/year, for steels that were exposed beginning in the dry and rainy season, respectively. Corrosivity was classified as C2 according to ISO. By using Mössbauer spectroscopy and Fourier transform Infrared analysis it was determined that the nature of the initial corrosion products was season dependent. Rust obtained from steels with exposure started during dry season was initially composed of amorphous and hydrated ferric oxyhydroxides; whereas during the rainy season it was a mixture of lepidocrocite (?-FeOOH) and goethite (?-FeOOH). After short periods, lepidocrocite and goethite constituted both types of samples. The amount of goehtite increased with time of exposition. No spinel phase could be identified.