Lightning strikes occur commonly during thunderstorms. It is exceedingly rare for a creature to be struck by lightning, though such an unlucky character would suffer between 4d8 and 10d8 points of electricity damage from the strike. Lightning strikes rarely produce forest fires in jungles due to their humid nature, but on the plains or in dry areas it’s possible for a strike to ignite a wild fire.
Pathfinder Chronicles: Heart of the Jungle. Copyright 2010, Paizo Publishing, LLC; Authors: Tim Hitchcock, Jason Nelson, Amber Scott, Chris Self, and Todd Stewart.