Mismatches between the timing of key life history events and optimal environmental conditions have emerged as an important threat to biodiversity, yet the evolutionary dynamics of most seasonal adaptations remain poorly understood. We have used extensive museum archives to map geographic clines in polymorphic winter white versus brown seasonal pelage camouflage of several species against local climatic variables, identifying global regions that may foster evolutionary responses to rapidly changing climates. Building on this overarching framework, we have begun to independently dissect the genetic underpinnings of locally adaptive winter coat color in several systems. In the snowshoe hare, we have combined population genomic association mapping with pedigree analyses and functional genomic studies in captive animals to dissect the genetic basis and evolutionary history of alternative winter white versus brown pelage morphs. Our results reveal that local adaptation of seasonal camouflage in hares has been shaped by gene flow (introgression) between species and convergent. Ongoing work in white-tailed jackrabbits and dwarf hamsters provide further insights into the genetic and evolutionary underpinnings of this dynamic form of phenotypic plasticity. Collectively, our studies provide some of the first insights into the genetic basis of a seasonally flexible trait for which the links between genotype, phenotype, and fitness are well understood. These findings yield important clues into how this crucial component of seasonal flexibility may respond to rapid environmental changes in snowshoe hares and other species.