Evaluating weather derivatives requires a different approach from that used for evaluating common financial products. One reason is the difficulty of replication, as temperature, rainfall or wind is not a traded asset. Consequently delta neutral techniques cannot be used and, in addition, there is a lack of liquidity in some temperature contracts. Therefore a number of market participants have started to use an actuarial approach when dealing with weather derivatives. Extracting and de trending heating degree days or cooling degree days from data, and then fitting a distribution to the events, makes valuation possible based on the expectation of the loss plus a given risk premium that reflects the sensitivity to risk. However, in doing so, a number of problems arise. These stem from the fact from that, in most cases, a maximum of 40 years of data is available. Some of these issues include:
March 19, 2001