If you want to see the desert pick a fine day and go to the desert. It will be cloudless, hot, and asleep and pretty much as you expect it.
If you want to be in the desert while it is awake and alive and changing its own character–go when there is drama in the skies and in the wind. Go when its army of clouds cast unshaped shadows of camouflage on its colored hills. Go when rain is pouring down from the heavens in patches and flooding the landscapes and carving the canyons and washes. Go when the wind is blowing sand that scars its cliffs and uprooting the Joshua trees that have become old and weak. Go while the desert is growing, reshaping, and in a dubious struggle with itself. Go then.