Any practical (e.g. easily implementable in R) methods for predicting the values for a given time series that account for additional/external variables influence ?
For example, the no. of orders for a restaurant business can be treated as time-series - but the future orders might get affected by any holidays, discount offers and weather so on. Given data about the no. of orders for each day and the weather on that day for the past one year, how to predict the no. of orders for the next couple of days given the weather forecast?
Similarly, load on a power grid can be viewed as a time-series and predicted based on history, but often any upcoming festivals and special occasions may influence the usage.
Any methodology to take these additional variables into consideration while predicting time-series?