Hot no matter what time of year you go--and for us used to the mountains, it gives a rare taste of what other terrains are like. Whew! Insufferable. Saw some pretty cool lizards the second time I went up.
It's good to go to this area in the very height of Spring (which is about January). Then the barren ground is covered with subtle little colorful flowers. Very pretty.
I've hiked to the oasis several times. It is a nice rest day hike. If it has been a wet year the wildflowers in the washes along the trail are fantastic! Great views, also, and the oasis is a fun place to hang out.