Forecasting and prediction are an inherent challenge for time-dependent dynamic processes, but have been implemented with greater or lesser success in systems as varied as financial markets and weather systems.  Phenomenological forecasts assume that the near future will be similar to the present, and the value of the present as a predictor gets weaker for more distant forecasts.  For this reason, the value of the stock market today is, on average, a good estimate of the value tomorrow, but a poor indicator of the value next year.  Many processes, including infectious diseases, tend to exhibit seasonal patterns. So for example, the seasonal increase in rate of influenza-like illness in January in the northern hemisphere can reasonably be predicted based on the repeatable pattern over the past several years.