Variability of Weather Windows in the Taiwan Strait and Their Linkages to Various Climate Drivers

Previous studies of offshore operational weather windows have typically relied on relatively short records (often less than a decade), limiting the characterization of low-frequency variability and its climate drivers. Here, we use more than 60 years of ERA5 reanalysis data to examine weather-window variability relevant to Taiwan’s offshore wind development and to identify the dominant climate processes governing this variability across timescales. Summer months provide the greatest number of operational weather windows and exhibit relatively stable year-to-year variability, making them the primary season for offshore operational activities. Interannual variability of June-July0August mean weather-window counts is dominated by a coherent regional wind pattern across the Taiwan Strait, with secondary contributions from modulation by the western North Pacific summer monsoon, ENSO, and episodic tropical cyclone activity. Together, these multiscale processes explain more than 50% of the variance in summer weather-window availability. Notably, during the period corresponding to the onset of Taiwan’s offshore wind development (2018-2024), summers have exhibited near-maximum accessibility relative to other time windows in the 60-year record, indicating that such favorable conditions may not persist and should be considered in long-term planning. Outside of summer, weather-window variability displays pronounced low-frequency behavior, including decadal oscillations and trends, with transitional months (e.g., October) associated with the Pacific Meridional Mode and colder months modulated by ENSO. These results highlight the importance of accounting for low-frequency climate variability when assessing offshore operational risk, with implications for reducing weather-related delays and supporting sustained progress toward offshore wind deployment goals. The framework presented here is transferable to other offshore wind regions with appropriate regional adaptation.