Reading the skies over the weather derivatives industry is difficult these days, such is the mix of sunshine and cloud. The collapse of energy giant Enron in late 2001 caused some market participants to reassess their commitment to the business. BNP Paribas and IntesaBci have left the market, while, according to traders at other firms, energy firm Aquila could be unwinding its weather book as part of an effort to boost its credit rating.

But despite these big name departures