Should be an easy question but Google failed me.
When using ANN for series forecasting one often uses may variables. For instance the number of shoppers might be determined by the previous number of shoppers and the previous weather conditions.
I have only ever seen ARIMA models used with one variable i.e. the number of shoppers.
Is this a feature of ARIMA models? do they only use one input (so to speak).
additional info: I've been using the ARIMA implementation provide by the Forecasting package for R. If is is possible, links to how to this is done with the forecasting package would be greatly appreciated.