No disrespect to the other person who answered but that is not correct and I have researched this. This is common regardless of where you are or if you car is kept in a garage. My car looks brand new and just turned 32,000 miles (7.5 years). My dash cracked after 4 and Toyota mearly told me I was out of warranty. Will never buy another Toyota product. My response to another post is below.
I have a 2006 in Tampa with the same problem. So does my dad. We have hit the dealer and the corporate office and all we got was for them to open a case and tell me that my care wasn't under warranty. I am not a nitwit, I know my car isn't under warranty I explained. They were surprised I thought they should do something. Despite our vehicles not being under warranty certain things shouldn't happen like the dash cracking as these do. My car is never outside except while driving. Even my work has a garage. My car has 32,000 and the body is as new. I have had 10 Honda's over the years and Honda takes care of their customers even when not under warranty. I had a 1978 Civic and in 1984 I got a mail saying that the hoods had a peeling paint issue and I could bring mine back for a repaint. Not under warranty either. My mom's Acura was 5 years old, went in for an oil change and the tech noticed she had a tear in her leather seat. Said that shouldn't have happened and ordered her a replacement. See my theme here? I will never buy another Toyota product, Lexus/Scion etc. Be great for you to call and complain to their corporate. Maybe you will tip the scales and they may move on this. Honestly, if they even did anything like.......if you pay cost for the dash we will install for free or discount etc. I was told I could get a new one istalled at my dealer for around $2,500. Anyway, long winded but you are not alone and all their cars have this issue.
Have a dash cover and have tinted windows. Also have had 3 other previous cars in the hot sunny weather and none ever had the cracks this car has. This car is garaged. 2 of my other past cars did sit out in the sun and never got cracks. This is clearly a poor quality made dash problem in Toyotas.