Climate extremes may occur throughout the year with large consequences for ecosystem functioning and feedbacks. Early snowmelt and drought often precede arctic fires, which in turn may degrade permafrost and thereby influence ecosystem functioning for many years post-fire. Overwintering "zombie fires" in the Arctic, which smolder from one fire season into the next, examplify the complexity behind extreme events and their consequences. More generally, extreme events during one season may have extended legacies during subsequent seasons and years. These legacies depend on ecosystem characteristics and organismal traits. All of this plays out against a background of warming trends and changes in extreme weather phenomena during and outside the Arctic growing season with organisms that are evolutionarily adapted to strong but predictable seasonal patterns.