Subgrade soil plays a very important role in the construction of roadways. Before the use of asphalt in the construction of roadway, roads were being constructed based on experience. The introduction of paving asphalt in road construction has led to the development of engineering procedures and designs for the methods of construction. The resilient modulus of the underlying material supporting the pavement is now considered as a key material property in the AASHTO mechanistic-empirical design procedure. Attempts have been made by researchers to predict the Subgrade resilient modulus from laboratory/field experimental methods based on the soil properties. This research seeks to develop a model for predicting the subgrade resilient modulus due to environmental conditions by considering the seasonal variation of temperature and moisture content which affects the soil. The limitation of this research model is that it cannot be used universally since environmental conditions vary from place to place, however, it can be modified to suit other local environmental conditions. The detrimental effect of low resilient modulus of subgrade soil is observed in the damaged analysis.