Electrochemical impedance spectroscopy in 500-1100 mu m large liquid droplets containing chloride and sulphate ions has been used to investigate the local corrosion rate of galvanised steel. The objective was the empirical modelling of the corrosion rate as a function of temperature, electrolyte thickness, and chloride and sulphate concentrations. The first experiments showed that the corrosion time was one of the critical parameters; it was then included in the investigation. An empirical numerical model was obtained for steel and galvanised steel. The statistical model highlighted the respective importance of the five parameters on atmospheric corrosion and gave qualitative results in accordance with the literature. The statistical study also suggested that the corrosion potential was easier to model than corrosion currents.