Four simulations (RANGEPACK Herd-Econ) of a beef weaner enterprise, each subjected for a period of 30 years to a different rhythm of the long-term variation in rainfall and simulated dry matter production (PUTU 11) of veld at Glen, were compared. These different rhythms were based on the historical sequence of good, average, poor and bad years over a period of 63 years. Management inputs for the beef weaner enterprise were identical for each comparable defined climatic year. The basic sets of biological variables for the cattle, namely, reproduction and growth rate of calves, heifers and cows, were identical for each simulation and differed only with respect to the specific defined sequence of climatic years that prevailed in each simulation. The same input costs and produce prices were applicable in all four simulations. Variation in climate, as determined by the specific rhythm of successive climatic years during each simulation, had a major influence on the financial results. The accumulated annual cash surpluses (in ascending order) of Simulations II, IV and III were (after 30 years), respectively, 6.8%, 12.8% and 14.1% higher than that of Simulation I. The consequences of poor and bad years, but also of the good years, which may have occurred at random during the lifetime of a livestock producer, are discussed.