“Zombie fires” are fires that ignite in one fire season, smoulder through the winter months under the snow, and re-emerge early in the spring before lightning and human caused ignitions begin in earnest. Northern fire managers prefer the term “overwintering fires,” which is more technically precise. It also avoids stoking the pervasive negative perceptions regarding wildfire, which in the boreal is an essential agent of forest renewal and health. …Are zombie fires something to worry about? …Fire behaviour refers to the way a fire burns. This seemingly unusual fire behaviour was previously of limited concern as overwintering fires are hard to detect and were relatively infrequent. As such, we know very little about these fires or their potential impacts. However, as rapid climate warming drives larger, longer and more severe wildfire seasons across the boreal, overwintering fires are becoming more common, and concerns by fire managers and scientists alike are increasing.