I haven't had any issues with summer temps in the 90's. I would avoid black pots and containers and stick with something lighter in color if possible.

I live in Florida, zone 10. I understand what you are talking about. I have many plants in containers and it is a challenge growing in full sun.

Most of my containers are grown in clay pots which do allow 'breathing' through the porous clay. I do grow my potted plants in a loose mix of orchid bark and perlite, miracle grow for the peat mix. This allows air exchange and ventilation.

Most of my large planters contain trees and the canopy shades the pot. For smaller containers containing annuals, I grow them in partial shade.

I have found plastic containers which are thermal types. There is a layer of air or Styrofoam between the layers. They are light weight but keep the plant roots protected from intense heat. The sun shines down. Whatever you are growing should shade the roots.

Look in Walmart and other big box stores for the type of pot I describe. You will see the difference. The walls are thicker but the pot is quite light. Great for large trees which need to be moved around.

Jane