The most I have ever gotten out of a lead acid battery is maybe 3-5 years, depending on the vehicle. The 4Runner has been a consistent 3 years, the Camry is every 5 (So far, this is battery number 2 on me that I am about to put in).

I would think the hotter weather of Cali would make the battery deplete faster then here in the northeast with the bitter cold to extremely hot and humid days.