It will be in the 20’s where I live.
Well, what sort of plantings do you have, are they tropical varieties, or are you talking southwestern desert, what do you guys call it, xeriscaping or something like that?
I can only speak for the southeast, as far as preventing or limiting frost damage. The poster above who mentioned spraying to create a thin coating of ice is correct. In the orange groves, sometimes they use “smudgepots,” to put out a little heat and smoke to limit the frost.
If you’re only talking one night, and don’t want to trust that the wind will prevent frost from settling, get garbage bags or lawn and leaf bags with the built-in pull ties, put them over the plants and then pull the tie down reasonably tight and tie it off, but not tight enough to potentially damage the plants. If this unusual cold is going to settle in for a while, you might want to insulate the roots and lower portions of the plants; we in the southeast would typically mound mulch or pine needles around sensitive plants.
Does this help?
Depends on how long it stays in the 20s. The wind really plays no significant role. Throw sheets over the plants and tie it at the base with twine or anchor the corners with something heavy.