The same ground that broils in the afternoon can be near freezing by dawn. The desert's daily temperature swing runs dozens of degrees inside a single turn of the day, and it is a defining feature of a dry climate. What you feel here is not an average; it is the distance between two extremes packed into one day and one night.
Water vapor is the missing blanket. Humid air traps outgoing heat at night and holds a place warm after dark, but the desert's dry, clear air does not, so once the sun is down the ground radiates its stored heat straight out to space and the temperature falls fast and far. Clear sky by day lets the full sun in; clear sky by night lets the day's heat right back out. The same dryness, working in both directions.
There is a second mechanism, and it decides where the cold collects. Cold air is denser than warm air, so at night it slides downhill off the high ground and pools on the flats and in the low basins, the way water finds the bottom. That means the open flat can be markedly colder at night than the slope just above it, a lake of the coldest air settling into the lowest ground while the hillside stays warmer. It is exactly this drainage that lets frost-sensitive plants live on warm slopes and die on the cold flat below them.
For anyone living on this ground, that flips an intuition. Height on a slope beats the flat at night, so a rise of only a few feet onto a hillside can be the difference between a frosted spot and an unfrosted one. Where to plant a tender tree, where to park, where the cold will gather, are all questions the slope answers if you read it.
The practical upshot is that the desert is really two climates a day. It asks for shade and water at noon and a coat by dawn, and the swing, not the daytime high, is what catches newcomers out.
Watch where the frost sits at first light. White on the flat and clear on the slope maps the cold-air drainage across your own ground.