This study focuses on analysing weather windows in the Polish Exclusive Economic Zone of the southern Baltic Sea, assessing the spatial and temporal variability of sea conditions that influence the accessibility of marine areas for research and offshore operations. The research examines monthly averages and maximum lengths of weather windows across the study site using significant wave height (Hs) thresholds of 0.5 m, 1.0 m, 1.5 m, and 2.0 m. The analysis shows substantial differences in accessibility depending on the location, time of the year, and wave height thresholds, with the highest accessibility observed for Hs ≤ 2.0 m in coastal areas throughout the year. In contrast, winter months present the lowest accessibility, especially for Hs ≤ 0.5 m, falling below 5% offshore. The study underscores the importance of such analyses for optimising the scheduling of marine operations, risk management, and cost reduction, particularly for pre-investment marine surveys and offshore projects. These findings offer valuable insights into weather risk mitigation strategies, enabling more efficient planning and execution of research and commercial activities at sea.