For California, this is such a rare occurrence that I don't have a clear answer.
Most homes are on slabs so you just need to worry about pipes in the walls especially if they039;re running outside. Just this week we've been down in the 20's but that's so rare. Keep the home at about 50 degrees, even if it's vacant, wrap the outside faucets, as the home inspector had probably indicated on his report, and you should be fine. Again, I'd review your home inspection report for any areas that might have a risk in this rare weather we're having.