From the Chron:
http://www.sfgate.com/...Country-12269146.php "
12:45 p.m. Officials say power lines possibly sparked some wildfires, drought helped spread it: As officials probe the source of a series of Northern California wildfires that left 21 dead, the cause remains unknown, but there were reports that strong winds had knocked down numerous power lines between 9:20 p.m. and 10 p.m. on Sunday night, about the time the fires broke out in Napa and Sonoma counties.
“We are investigating a number of potential causes, including whether reports of power lines falling down and electrical transformers exploding Sunday night may have caused some of the wildfires in the region,” said Janet Upton, deputy director of the California Department of Forestry and Fire Protection, also known as Cal Fire.
Cal Fire Chief Ken Pimlott said at a Wednesday news conference that the fires were driven by a “critically dry fuel bed” across the state. “We are still impacted by five years of drought,” he said. The recent wet season that brought California out of the drought was ineffective in tempering dry, explosive conditions, Pimlott said."