Paul - from what I have read, California gets more rain in the "wet" season than Arizona does. This allows the underlying brush to grow taller and thicker. Then in the dry season, the additional dead grass is simply more fuel for the fire.
Then the stronger winds make it more difficult to put it out.
It amazes me how California always seems to be the hardest hit state in the US every year when it comes to wild fires. I might have to look up that stat but it certainly seems like when the Santa Ana winds pickup the fire danger ramps up to a 10. One would think as dry as Arizona, Nevada and New Mexico are they would be high candidates for fires. Colorado gets its share too but it’s California we hear about the most. Paul