Rice production is central to the Vietnamese economy, not only in terms of contribution to Vietnam’s GDP, but also to the food security of its population. However, Vietnam is one of the countries most threatened by climate change in the coming decades, and its rice production. This paper focuses on rice yields and investigates their evolution over time and between provinces over the period 1987-2015, depending on climatic conditions. Special attention is devoted to the impact of heat stress. This impact is measured considering the potential adaptation of farmers to these extreme events. To this end, a damage function allowing for spatial and temporal heterogeneity in rice yield responses to heat exposure is estimated. Data descriptive analysis shows that the provinces with favorable conditions for rice growth are also those that face the most risk of heat stress. The main result of the estimation shows that these provinces have adapted well to heat stress conditions over the period studied, but that their effort to adapt begins to decrease when the risk of heat stress becomes too high. Taking adaptation into account then makes it possible to qualify forecasts of changes in rice yield due to climate change, which are usually made in the absence of any adaptation.