California coastal sage scrub (CSS) supports a multitude of native plant and animal species in the coastal range of central and southern California. CSS distribution has been reduced to an estimated 10% of its original extent since historical times. Previous studies have shown that climatic variables such as temperature and precipitation strongly influence CSS distribution. We here parse out the respective roles that climate and human development have played in determining CSS’s current distribution using species distribution modeling (SDM). We also determine how future climatic change will influence the distribution of CSS. To answer these questions, we identified the historical distribution of CSS in California using data from the 1930’s Weislander Vegetation Survey, determined its preferred climatic niche based on 9 climatic variables, and projected the resulting SDM into today’s climatic regime. Next, we mapped on modern (2010’s) observations of CSS using the U.S. Forest Service’s CALVEG vegetation data to compare CSS’s estimated preferred range to its actual current distribution. Using our SDM, we then predicted how the modern range of CSS would change by 2050 using CMIP climate projections. We found that the climatic envelope of CSS remained relatively stable when projected from a historical baseline into both the present and future. This indicates that climate change may be less important in determining the niche of the CSS community than previously thought. This discrepancy may be a result of land use change over recent history. Modeling the niche of CSS reveals the influence that human impact and climate change will have on a threatened ecosystem.