There’s a lot more rain than that in the desert. Then of course there’s “after the rain”, puddles can stick around a long time. The real question for this is what’s wrong with aluminum piping, light, cheap, strong, has no problem with rain or really any weather.
Since you brought it up, there is a long used axiom in the bicycle industry. There is strong, light, and cheap. You can pick any two you want.
Did you check out the tires?
And that occasional rain in the desert ~ I proposed a large plastic bag to protect the bicycle until it drives up, which it will, with more certainty than a snowstorm melting in a cold winter.