This paper describes a two dimensional model which permits evaluating the local thermal and geometrical properties during the process of frost formation. To achieve this objective it is necessary to know the local heat and mass transfer coefficients and hence solve the flow, heat and humidity fields. The solution is based upon converting the field functions in terms of the vorticity and stream functions. Once the heat and mass transfer coefficients are determined, a two stage model of the frost formation is used to determine the growth rate of frost layer. The numerical predictions were compared with existing numerical and experimental results and good agreement is found. Other results demonstrate the variation of frost density, frost thickness and the temperature field are presented and discussed.172135146