1. To tell what is coming on the basis of observations, study, or experience: Cooler weather is forecasted for tomorrow.
2. To plan or to decide ahead of time: The weatherman forecasts on the basis of atmospheric conditions.

The act or process of predicting on the basis of present trends of probable events that will come: Daily forecasting is a matter of charting current atmospheric conditions in order to be able to foresee the state of the weather for the near future.