radiator leak cause question

With plastic tanks it doesn't take much effort to make them leak.
If the core-support was hit hard enough to make it diamond shaped, you can bet the plastic will leak, sooner or later.

If your cooling system is operating properly, the ambient temp will not affect it.
If the pressure in the tank exceeds the rating of the cap, the excess pressure is supposed to be vented, that is part of the purpose of the cap,
My rad is a 1973 model, and, altho designed to run at 15psi when new, I only run a 7psi cap, and so that antique rad continues to hang together.

IDK why your tank burst, it could be a combination of factors. I hate that stupid idea of plastic tanks. there is a very expensive chunk of metal depending on the rad. Manufacturers should know better.