By Paul Homewood
https://statesummaries.ncics.org/chapter/ca/
Clearly, rainfall is not becoming more extreme there, despite claims to the contrary.
There is also this very interesting graph on drought trends since 1000 AD:
Current drought trends are little different to most of the 20thC. Looking further back in time, California has suffered much more severe droughts for most of the last millennium.
Climate Collections 