The environmental exposure dramatically influences the performance of externally applied Fiber Reinforced Polymer (FRP) in the long run. Temperature and humidity are two common environmental factors that alter the bond behavior of the FRP application. This paper summarizes the observations of different researchers regarding the effect of temperature and humidity together (also known as the hygrothermal effect) and separately on the durability performance of the FRP-Concrete bond itself and its elements individually. Furthermore, a comparison of performance between FRP Laminate and sheet has been presented for hygrothermal environments. Moreover, different approaches by researchers to model the FRP-Concrete bond, followed by the efforts to incorporate hygrothermal effects in it, are discussed. Finally, some of the authors’ observations and directions for potential future work have been stated.