Here's the story...when growing tomatoes in containers the containers need to be large enough to hold lots of soil. Minimum of 15 gallons. Tomato roots are huge and they need the soil volume to feed, support and get moisture to them. The least expensive and easiest to find pots around here happen to be black plastic. So, I use them. Lots of them.
Now, it also gets quite hot here in the west San Fernando Valley. Couple that with the fact that my containers are sitting on a former basketball court and you'll get an idea of just how hot my containers and, therefore, my plants can get.
Here's what I do to help keep my plants from overheating:
The pots all go up on "pot feet". I think this helps with drainage and it also creates a small gap between the pot and the heat emanating off the concrete. Then, each pot is individually wrapped in burlap. I buy burlap bags at the local feed store and cut them open. They make it almost twice around the pots. Then I use garden staples to hold them in place. The pots remain wrapped for the entire season. When it's really hot I water the bags to help cool them down and hopefully cool the pots a little. The point here is this: black pots absorb heat and on really hot days the root balls will cook! Tomato leaves and fruit like some heat but the roots do not.
Last, I follow 3 different weather services daily. When the forecast gets anywhere near 90 I put up shade cloth. It drapes over frames made of pvc pipe and doesn't look pretty. But, we all have our priorities, and mine is to protect my tomato plants as much as possible.
Hope this helps! Keep your questions coming...