This study examines the trend in wave parameters over available annual records in the Bay of Biscay, where EWTEC 2023 is being hosted. There have been various renewable offshore energy projects in the 21st century in this region, such as the OWC (Oscillating Water Column) plant in Mutriku , or BiMEP (Biscay Marine Energy Platform) , the infrastructure for testing ocean devices in Armintza, where better characterization of the wave resource could help to provide design information to developing wave energy technology. Other studies  have shown that wave height has increased in recent decades, as well as the frequency at which extreme waves occur, which affects the fatigue experienced by deployed devices. The aim is to study the effect of the maximal wave height, its frequency, and loads on monopile cylindrical structures, which are basic component structures for wave energy converters and offshore wind turbines. The effect of this evolution, against these generic structures in offshore wind and wave energy devices, is studied using the 20th century reanalysis ERA20 (1900-2010) of ECMWF (European Centre for Medium-Range Weather Forecasts) . A significant increase in two forces, drag forces and inertial forces, of up to 15%, is computed over 110 years at a gridpoint near the Western Basque coast, which constitutes a strong positive slope that can be also associated with climate change, and has strong implications for the design of new marine renewable energy technology.