Identifying ecologically important traits that drive adaptation to different climatic conditions and how these vary across environments is fundamental to understand how species cope and respond to current and future climate change. Yet, knowledge of such traits remains scarce. In the Mediterranean region, plant species from the Lamiaceae family produce essential oils rich in monoterpenes. Monoterpenes protect against climatic stress, and many plants are polymorphic for monoterpene compounds in the oils. In Thymus vulgaris, different chemical types (chemotypes) have previously been documented to form two ecotypes: a phenolic ecotype adapted to warm and dry summers, and a non-phenolic ecotype adapted to tolerate winters with severe freezing. Here, we report on a large-scale mapping of natural chemical variation within and across four widespread aromatic Mediterranean species (T. vulgaris, T. zygis, Oreganum vulgare, and Satureja montana). Covering a large gradient of climatic variation, we combined our own data of chemical variation in T. vulgaris collected at different altitudes across Southern France with a comprehensive literature review of studies from the entire the Western Mediterranean region. By integrating this data with historic climatic variable records, we reveal that phenolic and non-phenolic ecotypes of T. vulgaris across its native distribution in the Mediterranean region. Moreover, we found that the ecotypic variation extends across all four species, suggesting a broader pattern of climate-driven convergent phenotypic differentiation within Lamiaceae family.