California law prohibits concealed carrying of anything that can be readily used as a stabbing weapon. Most interpret that to mean any fixed blade knife. Theoretically it could also mean a screwdriver or ballpoint pen. The law is vague at best. Open carry should be fine but check with your local laws as there are length restrictions in some cities and counties (Los Angeles has a 3" limit I believe). Also any blade disguised as something else (belt buckle, writing pen, lipstick, cane sword, etc) is expressly forbidden.
Carrying a fixed blade knife in a neck or belt sheath while out hiking, camping, hunting or fishing is legal everywhere in California, and there is no length limit. Even in LA, there is an exception in the law for work, recreation, or religious purposes. So if you're a Sikh, go ahead and wear your kirpan in LA.