Plant cold hardiness varies dynamically throughout the dormant season, primarily in response to changes in temperature. Taking advantage of an extensive database of grapevine (Vitis spp.) bud hardiness measurements, Ferguson et al. describe the development of a robust, discrete-dynamic model of bud cold hardiness for three Vitis genotypes. The model will aid in the anticipation of and response to potential injury from fluctuations in winter temperature and from extreme cold events.