Bay checkerspot butterfly (Euphydryas editha bayensis), a federal-threatened subspecies of Edith’s checkerspot (E. editha), is endemic to the San Francisco Bay Area and is currently restricted to San Mateo and Santa Clara counties. From 2008 to 2019, focused Bay checkerspot butterfly surveys were conducted annually at an approximately 2,150-acre private ranch property, located in San Jose, Santa Clara County, California. We used MaxEnt modeling to compare the relative contributions of landscape and climate factors to Bay checkerspot butterfly distribution in years with larger than average and smaller than average adult population sizes. In large population years, the most important factor in determining distribution was distance from suitable habitat, defined as serpentine soils supporting both host and nectar plants. In small population years, the majority of BCB observations occurred in suitable habitat so the relative importance of this factor was lower. Elevation within suitable habitat had greater relative importance in small population years compared to large population years. Other examined factors, including land cover type, solar radiation, wind speed, topographic position, and slope, contributed little to either model. The results of this long-term dataset are consistent with the metapopulation model of population dynamics.