Density Forecasting for Weather Derivative Pricing: A Comparison of GARCH and Atmospheric Models

Weather derivatives enable energy companies to protect themselves against weather risk. Weather ensemble predictions are generated from atmospheric models and consist of multiple future scenarios for a weather variable. They can be used to forecast the density of the payoff from a weather derivative. The mean of the density is the fair price of the derivative, and the distribution about the mean is important for risk management tools, such as value-at-risk models. In this empirical paper, we use one to 10 day-ahead temperature ensemble predictions to forecast the mean and quantiles of the density of the payoff from a 10-day heating degree day put option. The ensemble-based forecasts compare favourably with those based on a univariate time series GARCH model. Promising quantile forecasts are also produced using quantile autoregression to model the forecast error of an ensemble-based forecast for the expected payoff.