Abstract: A method and system for time series forecasting on a big data set are provided. The method includes receiving a plurality of time series, each of the time series representing a historical demand pattern for an item, performing a domain-based segmentation to identify a plurality of statistically forecastable time series from the plurality of time series, grouping the plurality of statistically forecastable time series into one or more clusters, for each cluster, generating an aggregate time series based on time series included in the cluster, performing a future demand forecast at a cluster level by performing time series forecasting of the aggregate time series for each cluster, and determining a future demand forecast for each item based on the time series forecasting of the aggregate time series.