Operational Weather Windows for Offshore Wind in the Taiwan Strait: Long-Term Variability, Regional Wind Modes, and Climate Linkages

Abstract. Previous studies have either focused on shorter operational records or on ENSO-related variability over more limited periods, leaving the role of regional wind modes and longer-term climate context less explored. 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 proximal regional wind modes and large-scale climate linkages associated with this variability. Compared with winter, summer provides the greatest number of operational weather windows and exhibits relatively stable year-to-year variability, making it the primary season for offshore operational activities near Taiwan. Interannual variability in June–July–August mean weather-window counts is dominated by two regional wind modes across the Taiwan Strait, with secondary contributions from episodic tropical cyclone activity and broader climate linkages involving the Western North Pacific summer monsoon and ENSO-related sea surface temperature signal. Together, the regional wind modes, tropical cyclone activity, and climate-linkage indicators account for more than 60 % 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 exhibited near-maximum accessibility relative to other 7-year windows in the 65-year record, indicating that such favorable conditions should not be assumed to persist. These results demonstrate the value of long-term weather-window analysis for addressing how offshore wind operating conditions are associated with broader climate variability and for supporting risk-informed construction and operations planning.