In three studies (N = 1,055), we investigated the determinants and consequences of the perception of infection risks during the early and later outbreak of COVID-19 in Germany. Individuals’ perceived COVID-19 infection risk was reasonably in line with experts’ assessment but changed over time. The probability of the rare event of getting severely sick and hospitalized was overestimated. Overestimation increased in the exponential growth phase of the pandemic and later on decreased again, showing an inverse U-shaped pattern. Individuals showed biases in their risk perception concerning overconfidence and the underestimation of exponential growth of infection cases in the early phase of the pandemic. Forecasts were more accurate after the growth curve had flattened. Risk perceptions increased with perceived dread and tended to increase with perceived control over infection, the evaluation of scientific and own knowledge about the pandemic. Approval for the introduction of stricter governmental measures and acceptance of future vaccination measures was mainly influenced by rational utilitarian factors of risk perception (probabilities and utilities of outcomes). These rational influences were mediated by dread, but dread had an additional potentially irrational effect. Adherence to governmental recommendations was mainly driven by dread and positive expected long-term consequences of the measures. To a smaller degree, adherence increased with perceived personal consequences of infection and decreased with negative expected short-term consequences of these measures. Implications for theory development are discussed and recommendations to handle virus outbreaks are derived.