Certified GKH Gardening Expert
Certainly, plenty of water will help. You also may want to try sun shades. These can by made with very thin fabric that is opaque and allows plenty of light through, but decreases its intensity some. Just set the fabric up over the plants like a canopy. Mulching the base of the plants will also help.
Also, look for plants that are bred for hot areas. For example, with tomatoes, look for varieties that come from Africa or the Middle East. Some varieties I know do well in heat are Walter, Bingo and Spring Giant.