Commuted by bike for 16 years in Tucson.
Got rained on maybe a dozen times.
No need to invest in raingear. Get a 30 gallon plastic garbage bag. Cut 3 holes in it. One in the center for your head and 2 on the sides for arms. Voila: Instant rain protection!
Have ridden in 117 degrees with 2% humidity . . . that's worse than rain!