I'm throwing a blanket over the dwarf lemon tonight because the overnight expected low for 90027 is supposed to be 36°. The last time it was expected to be that low, it did indeed freeze over on the terrace. If you live in any shady canyon or Sunland Tujunga and have citrus still on any trees, I would recommend covering it too.
Fortunately, nothing's on the verge of blooming. It's a good time of year for a frost.