Since it gets so hot here in the desert, it often surprises people that it's the ability of a plant to withstand cold that is the real determining factor of its ability to live here. By the way, in case anyone asks you, it's called the plant's *hardiness*, although I doubt anyone will ask you. That's the lowest temperature that a plant can stand. You can get that information on the tag of any plant that you buy at at nursery, or you can Google *hardiness* for any given plant. The USDA determines hardiness zones, based on how cold it gets, which goes from 1 to 13. Lately I've seen additional zones squeezed in as a, b. etc., but mostly this is zone 9, where the coldest it usually gets is in the 20s, although I've had friends who have seen colder temperatures in their yards.
As of November 1st, I've reduced my automatic watering down to once a week. After the winter solstice (Christmastime), I will turn the water off completely, and resume it again in late January or early February, depending on the overnight lows. The annual flowers and bulbs I will water all winter by hand. And we usually get some gentle rains in late December - I call them *Christmas rains*.
So, by January, even though it will be comfortable golfing weather, it will get to freezing or below at night. Start reducing the amount of water that you are giving your plants now, in November, and that will help them prepare for the cold days ahead. Keep your eyes on the overnight forecasts starting in late December and throughout January, to be prepared to cover your plants if there is a frost. I keep old sheets in my garage, although many years I haven't needed them at all.