Because of high fluctuations of tourism demand, accurate predictions of tourist arrivals are of high importance for tourism organizations . The study at hand presents an approach to enhance autoregressive prediction models by including travelers ’ web search traffic as external input attribute for tourist arrival prediction . The study proposes a novel method to identify relevant search terms and to aggregate them into a compound web-search index, used as additional input of an autoregressive prediction approach . As methods to predict tourism arrivals, the study compares autoregressive integrated moving average (ARIMA) models with the machine learning–based technique artificial neural network (ANN). Study results show that (1) Google Trends data, mirroring traveler ’ s online search behavior (i.e., big data information source), significantly increase the performance of tourist arrival prediction compared to autoregressive approaches using past arrivals alone, and (2) the machine learning technique ANN has the capacity to outperform ARIMA models.