The main target of the proposed work is to assess the expected wave energy dynamics in the coastal environment of the Iberian Peninsula. This study is motivated by the fact that the Iberian nearshore is considered among the most promising European coastal environments for wave energy extraction with experimental wave projects already operating there since many years. The near future period considered for this analysis is the 20-year time interval 2026–2045 under the Representative Concentration Pathway scenario 4.5 (RCP4.5). In parallel, in order to have a coherent degree of comparison, the results are compared with those corresponding to the recent past 20-year time interval 2001–2020. A wave modelling system based on the third-generation spectral phase averaged model SWAN (acronym from Simulating WAves Nearshore) was implemented for the entire North Atlantic basin and focused on the Iberian nearshore. Furthermore, calibrations and extensive validations of this wave prediction system have been performed. Thus, system reliability was evaluated both against buoy and satellite data and the results were found as having good accuracy. The wave energy data corresponding to the near future (2026–2045) are compared with those from the other 20-year period from the recent past (2001–2020). In this way, a comprehensive picture of the expected wave power dynamics in the coastal environment of the Iberian Peninsula is provided. The results show that there are no significant differences between the two periods considered, especially in the transition seasons (spring and autumn), both in terms of maximum values and also as regards the general patterns of the wave power fields. However, in the near future, a decrease of the resources is expected near to the coast in the summer season, compared to the values simulated for the recent past (from 12 kW/m to 9 kW/m). A contrary tendency corresponds to the winter season when for the near future we find a maximum value higher by about 14 kW/m than in the recent past.