[sbov]

I don't know what a "fire plain" is. But would you consider Oakland being in one? https://en.wikipedia.org/wiki/Oakland_firestorm_of_1991

The fire problem in California is basically anywhere there is any wilderness. The state inevitably gets dry and becomes a tinderbox.

[olivermarks]

Same as a flood plain, an area that has seasonal conditions that are likely to endanger the area. Example: The recent Santa rosa fires which took out Fountaingrove. An identical fire happened same time of year and wind conditions in 1968 when the area was mostly grassland. They are already rebuilding huge houses there after the recent fire.