An immense amount of work has investigated how adverse situations affect anxiety using chronic (i.e., average) or episodic conceptualizations. However, less attention has been paid to circumstances that unfold continuously over time, inhibiting theoretical testing and leading to possible erroneous conclusions about how stressors are dynamically appraised across time. Because stressor novelty, predictability, and patterns are central components of appraisal theories, we use the COVID-19 crisis as a context to illustrate how variation in the phenomenon's patterns of change (specifically, total cases [average level] but also the rate of linear [velocity] and nonlinear growth [acceleration] in cases) influence anxiety. We also show the implications of anxiety for next-day functioning at work. These effects are tested in data drawn from a sample of employed adults in a daily diary study conducted in four overlapping waves. The data span the emergence, exponential rise, and initial tapering of the virus in the United States (February 10, 2020 to April 28, 2020). Our results show that although the impact of level of COVID-19 cases on anxiety decreases over time, the effect of change in cases (velocity and acceleration) increases over time. Anxiety is then associated with next-day work functioning (engagement, performance, and emotional exhaustion). (PsycInfo Database Record (c) 2021 APA, all rights reserved).