I live in AZ, doesn't get any sunnier than that. So far no issues but I haven't done more than just a wipewith dry cloth on the dash. I'll let you know if I notice a difference after a clean up this weekend.
Even in a Virginia winter I've had this issue, lol. I have used a protectant, so that isn't helping, but I'm considering putting something down to keep it from glaring... Let me know what you find, I just don't want to put down one of those huge carpet dash covers. lol