This article examines the seasonal pattern of television viewing. A mathematical model that describes the frequency of television viewing as a function of time is presented. We hypothesize that it is composed of three components: an oscillation that describes the seasonal variation in viewing; a logistic translation, to account for the increase in viewing due to the diffusion of television; and a time-independent term. The model is evaluated with monthly data from the Nielsen Television Index (N = 460). It fits the television-viewing data, explaining about 99.9% of the variance in viewing. All three components are statistically significant. Next, the seasonal nature of television viewing is explored. It may be accounted for by environmental factors—temperature, precipitation, and daylight. The relations among these variables are demonstrated through spectral analysis. The implications for other cyclic processes in communication are discussed.