Forecasting biogeomorphological conditions for barrier islands is critical for informing sea‐level rise (SLR) planning, including management of coastal development and ecosystems. We combined five probabilistic models to predict SLR‐driven changes and their implications on Fire Island, New York, by 2050. We predicted barrier island biogeomorphological conditions, dynamic landcover response, piping plover (Charadrius melodus) habitat availability, and probability of storm overwash under three scenarios of shoreline change (SLC) and compared results to observed 2014/2015 conditions. Scenarios assumed increasing rates of mean SLC from 0 to 4.71 m erosion per year. We observed uncertainty in several morphological predictions (e.g., beach width, dune height), suggesting decreasing confidence that Fire Island will evolve in response to SLR as it has in the past. Where most likely conditions could be determined, models predicted that Fire Island would become flatter, narrower, and more overwash‐prone with increasing rates of SLC. Beach ecosystems were predicted to respond dynamically to SLR and migrate with the shoreline, while marshes lost the most area of any landcover type compared to 2014/2015 conditions. Such morphological changes may lead to increased flooding or breaching with coastal storms. However—although modest declines in piping plover habitat were observed with SLC—the dynamic response of beaches, flatter topography, and increased likelihood of overwash suggest storms could promote suitable conditions for nesting piping plovers above what our geomorphology models predict. Therefore, Fire Island may offer a conservation opportunity for coastal species that rely on early successional beach environments if natural overwash processes are encouraged. Plain Language Summary Predicting a barrier island's future characteristics is important for planning, particularly given that these areas contain habitats used by threatened and endangered species and are popular sites for housing and recreation. In this study, we combined five models to predict barrier island characteristics like elevation, beach width, and dune height under three rates of shoreline erosion at Fire Island, New York. Models were also used to predict how likely parts of the island were to be permanently flooded by sea‐level rise or to experience overwash with storms, where waves move sand deeper into the island. We found that Fire Island would likely become narrower and flatter while experiencing more overwash with storms as rates of shoreline erosion increase. These changes may lead to more flooding in housing communities and businesses on the island. However, models also predicted that beach habitats used by shorebirds like the piping plover would not flood permanently. Instead, they would move as the shoreline changes position as long as human structures like buildings or seawalls do not block sand movement. This migration of beaches and sand is important, as it also allows a barrier island to evolve and survive with rising sea levels. Key Points With increasing shoreline erosion and landward retreat, Fire Island was predicted to become flatter, narrower, and more overwash‐prone Beaches are expected to be least impacted and to replace other landcover types as they migrate with the shoreline Habitats used by piping plovers are expected to persist as long as development and stabilization structures do not limit beach migration