The impact of climate warming on coastal benthic fauna is already observed, but forecasting their long‐term fate remains challenging. This study uses δ 18 O shell data of specimens of five bivalve species collected at six locations and results from kilometer‐scale atmosphere–ocean climate model for the time intervals of 1987–2017 and 2070–2100, to estimate changes in bivalve growth phenology. All species will benefit from climate warming during winter, experiencing a longer growing season than currently. The growth of Aequipecten opercularis , Flexopecten glaber , and Pecten jacobaeus will decrease in summer, resulting in up to 3 months of reduced growth per year. Glycymeris pilosa and Venus verrucosa in the southern Adriatic Sea will be more affected than those in the north, with up to 4 months longer annual growth. These findings can inform adaptation plans for bivalve management in the Adriatic Sea but also in areas where the studied species are present.