The California Energy Commission (CEC) website has several interesting reports on issues related to the energy sector. Under the heading Joint Committee Workshop on Natural Gas Issues for June 16, 2009, for example, there is a report on natural gas volatility that asks the question: "Do accurate [natural gas] price predictions actually exist?"
Answer: "A comparison of natural gas price forecasts vis-a-vis actual prices does not yield encouraging results for the accuracy of long-range forecasts." (Emphasis is ours.)
You can find this and other studies here (along with Staff presentations).