The California part of the journey is safe - so long as you stay out of the gang-infested areas. Unless you cannot avoid it; then being in a tank and carrying enough ammo is advised.
Mexico - even Baja - isn't safe unless you are in one of the tourist towns - and have a flight directly to one of these locations. If you don't know the language and don't carry a legal concealed weapon or have a guide that does - expect the worse in any area that isn't in a tourism-protected mode area.
I was born in a border town (El Paso, TX) which are generally speaking - relatively safe - but that isn't anything like being in Mexico proper. The Mexican govt is very corrupt, so the police are no help - but a hindrance and will try to take advantage of any norte-americano if they can. The expression 'blued, screwed, and tatooed' comes to mind. You have been warned. I've also been in Tijuana via San Diego and it was clearly more of the same. You couldn't pay me enough money to go into the non-tourist areas without heavy artillery.
If I am going to chase this storm, I would need to know if its effects would be directly visible in S California; then I would go - too!
That is - I would go as far as the US border...
PM me if you want more specifics if necessary...