The rice-wheat rotation is the dominant cropping system in Bihar, where food security of the rural population depends heavily on the production of rice and wheat. In Bihar, climatic shocks induced by low temperatures and terminal heat stress can significantly affect rice and wheat yields. The present work evaluates the benefit of using the monsoon onset as the date for planting rice in reducing thermal stress on rice-wheat systems. High-resolution gridded crop simulations using the APSIM model were performed to simulate potential yields of rice and wheat using the monsoon onset and the farmers’ practice as planting dates. The monsoon onset was calculated using an agronomic definition and farmers’ practice dates were estimated using satellite data. Model outputs were analyzed in terms of planting dates, yields, and the incidence of low temperature stress on rice and high temperature stress on wheat by means of the APSIM yields limiting factors. The results show that the rice planting and harvest dates using the monsoon onset are in general 20-30 days earlier, decreasing the incidence of thermal stress in rice and wheat, and generating higher and more stable yields. These results can help design mitigation strategies for the impacts of climate shocks induced by low and high temperature events in the context of the advances in sub-seasonal and seasonal forecasting, targeting climate services for farmers in Bihar.