 Authorities in western states are warning of the rising risk of wildfires as hot conditions and low humidity dry out the landscape amid a protracted heat wave baking much of the U.S. California's top fire official says so far this year, the state has responded to more than 3,500 wildfires that have scorched nearly 325 square miles of vegetation. Blazes are also burning in Oregon, where the governor issued an emergency authorization allowing additional firefighting resources to be deployed.