I feel like the benefits you obtain through cold showers disappear after a while as you get used to them. That's similar to the benefits I felt of meditation.
I wonder, is this sarcasm or do you really consider 50 F as deep winter in Arizona? I get it that you are used to much higher temperatures but still...
Right now we have around 40 F in Prague and it is not even a winter yet. Cold showers are still fine right now.