In areas that get very high summer temperatures, you can grow certain varieties of tomatoes. Hundreds of tomato varieties exist, from heirloom specialties like Amish paste to modern hybrids such as Early Girl. Some tomatoes have been bred for hot climates: those that have not will drop their blossoms when the mercury rises into the 90s and above. For example, the varieties Oregon Spring and San Francisco Fog are designed for cooler summers, while Amish Paste and Solar Set are suited to very hot summers.
Start seeds of a heat-resistant tomato variety (see Tips), or search local nurseries for bedding plants. If you start your tomatoes from seed, do so in early spring--if your region gets frost, wait until after your final spring frost to plant young tomatoes in the garden. If you live in a frost-free zone, wait until early spring, when the days are longer and the temperature is warmer than it was in midwinter.
Plant your tomatoes in an area that receives filtered or partial afternoon sun. Although tomato plants need eight to 12 hours of sun a day, afternoon sun is the hottest and can sunburn and dry out your plants.
Mulch your plants heavily with compost, dried leaves or other plant parts. Mulch will help keep the soil moist and cooler than unexposed soil, and it will benefit the plants by giving them continual nutrients.
Provide partial shade in areas that get intense afternoon sun by hanging shade cloth over your tomato plants. You might tie the shade cloth from surrounding trees, or you can build a simple support frame from 2-by-2 boards or tree branches.
Water your tomato plants well, at least twice every week. Watch them closely during very hot days and give them additional water if you see them beginning to droop.