I didn't define the Overlook Fire as natural or not, I labeled it a wild fire. Maybe that's the wrong term, but when it rages to a point by where fire fighters were barely able to put it down, it's a danger to forest and friend.
Natural or not, wild fires are common enough to be of concern. As I posted above, I personally participated in two small fire fights above the Overcliff Rd in the late seventies. Both of these were presumed natural as they were well away from any trails.
Your local fire companies would have records of fire calls. If you are truely interested in more specific historical records to answer your querie, that's where you should seek more exacting data.