Techniques for seasonality-based anomaly detection and forecast are described. For example, a method of receiving a request to generate forecast for received time series data; performing a seasonality-based anomaly detection and forecast for the received time series data based upon the received request, the seasonality-based anomaly detection and forecasting to utilize a second data structure that reflect anomalies found in a first data structure on the input from the received time series data; and providing a result of the performed seasonality-based anomaly detection and forecast is described.