This Book is based on Research entitled "Coalesced impact assessment of climate change through simulation modelling (DSSAT model) for rice cultivars at south Gujarat" conducted by Nilesh J. Hadiya and Dr. Neeraj Kumar at N. M. College of Agriculture, Navsari Agricultural University, Navsari during Kharif season of 2015-16. In this research they have calibrated and validated two crop weather models namely CERES and WOFOST model, and also analysis sensitivity of crop with different weather parameters, calculated thermal indices.