The aim of this study is to identify which psychosocial factors of the theory of planned behavior better predict and explain the adoption of heat and flood adaptation behaviors by municipal authorities in the Province of Quebec, Canada, and to explore the cognitive structures motivating municipal officers to adopt adaptation behaviors. The results of structural equation analyses showed that municipal authorities’ attitude toward the adoption of adaptation behaviors (i.e., the degree to which the performance of an adaptive behavior is positively or negatively valued by municipal officers) and perceived control (barriers) over adaptation behaviors significantly contributed to the prediction of readiness to adopt the behavior.