This chapter discusses the impact which durability considerations and climate extremes play on the performance of wind turbine structures. An overview of the technological developments in wind energy production, both onshore and offshore, is provided. The rigorous design requirements and specifications, guidelines and codes of practice prescribed for design are discussed. The basis for computational simulations, necessary to model and assess performance is outlined. Characterization of extreme values is discussed and the impact of climate extremes on environmental loads is demonstrated. The impact of deterioration, in the context of the durability of wind turbine towers is evaluated in terms of the probability of exceedance of specified limit states. Finally, discussion is provided around optimal decision-making regarding design, operation and maintenance.