I'm no lawyer, but this is what I found:
"California Penal Code section 12025 does not prevent a citizen of the United States over 18 years of age who is not lawfully prohibited from firearm possession, and who resides or is temporarily in California, from transporting by motor vehicle any pistol, revolver, or other firearm capable of being concealed upon the person provided the firearm is unloaded and stored in a locked container
The term "locked container" means a secure container which is fully enclosed and locked by a padlock, key lock, combination lock, or similar locking device. This includes the trunk of a motor vehicle, but does not include the utility or glove compartment. For more information, refer to California Penal Code Section 12026.1.."
Sounds like it needs to be locked in your trunk too.