Having lived in California basically my entire life, I can say one thing pretty comfortably about the weather. In California, you are either:
a) In a drought
b) Just got out of a drought
c) Just about to get into another drought.
We just don't get much rain here. Granted, we do have the Sierra Nevada mountains and the associated snow pack and reservoirs that get filled by it. But, we're still very, very dry.
Also, our politicians have decided that protecting a small species of fish (the Delta Smelt) is more important than providing water to the central California farmers. If we reversed this policy, then we'd be much better off as far as our water supply goes.
And, our population is too squeamish when it goes to using reclaimed water. Our waste water processing plants have to process water to near drinkable levels to release the waste water back into streams. We'd be much better off (as far as water supply goes) if we just finished the extra processing and turned that water into water supply used in our houses. But, Californians are too "privileged" (in general) to consent to using this water in their homes.