Bromus tectorum L. (Cheatgrass, Downy brome) is an invasive grass that has recently proliferated within the Gunnison Basin, Colorado. This study examined variation in germination in response to temperature, storage duration, and habitat. Four populations within the Gunnison Basin were sampled. Seeds were kept in dry storage for 0, 4, 8, 12, and 16 weeks and then incubated at four different temperature regimes. Seeds in storage for zero weeks had low percent germination, while seeds in storage for 16 weeks had high percent germination. The optimal temperature for germination was room temperature, while the least favorable temperature regime was 5:10 °C. Within these general patterns, significant differences were found among populations in percent germination, but the differences decreased as seeds after-ripened. Seeds that were chilled prior to germination tests at the 5:10 °C temperature regime showed enhanced germination compared to seeds that were not chilled. Similar to what has been found in other studies, delayed germination at high temperatures may be an adaptation to avoid early summer germination. However, in contrast to previous reports, significant lower percent germination of high elevation populations at low temperatures may reflect adaptation to more variable summer temperatures experienced by Gunnison Basin populations of B. tectorum.