It’s not well understood, but Phoenix does have a Spring. And to clear up confusion, it doesn’t happen in January. Much of Spring happens when the solar year is right, in other words, in April and May.

Blooming Palo Verde
We have a beautiful tree here, called the Palo Verde. The tree has tiny leaves running along thin branches. These branches shed and re-grow, and they do a lot of it in April and May.
The Palo Verde has adapted wonderfully to the desert climate. The tiny leaves aren’t enough to provide photosynthesis in summer, so the trees have green trunks and branches–what the leaves can’t do, the branches can. Blue Palo

Dropped Palo Verde blossoms
Verdes and older Palo Verdes have brown trunks, but the vast majority have green trunks and branches.
Both Palo Verde tree types bloom profusely–small-ish yellow blossoms with red centers. As the blossoms age, they drop, creating snow-like drifts in the streets. It’s Phoenix’s yellow snow. And no, we don’t eat it, either, just like colder climates don’t indulge in eating their yellow snow!

Blossoms blowing along street

Drifts in the gutter