Hi Amber. Welcome to ATP!
I am from the other California central valley (San Joaquin) and it just HOT! If you plan to grow tomatoes in containers, find at least 10 gallon - the bigger the better - and then insulate them. If you don't work out a way to keep the roots cool, you won't be successful growing anything.
Tomatoes, given the chance, will root 6 feet deep. Most of their root mass is way down there. In the garden, deep watering once a week, after they are established, would be plenty. In a pot, you will be watering every day or every other day.
The cheap way to do it is find someone planting trees out of those big 15 gallon pots, and insulate it with a roll of that silver insulation used for ducts.
Another way is to buy a giant bag of potting soil, lay it flat and make a slit in the bag and plant. Remember to put a couple holes in the bottom for drainage. The plant will cover the bag and provide its own insulation. I found a picture for you:
https://www.google.com/search?...
My only other thought is that you grow at least one other type of tomato. If, for some reason, the San Marzano doesn't do well this year, you will have other options. Look for tomato plants that are "indeterminate". My favorite container tomato is Husky Red.
Daisy
