It depends upon a number of factors, variety being one of them. Andean varieties tend to like it cooler, so at least if there is a way to shade them, do it. The most important thing is to make sure they don't get too dry - if the leaves start wilting, be sure to give them a good soak right away. Recommend watering in the evening when it's cooler and the sun is at least partially down, to reduce evaporation rates. I'm in Ohio, so your weather is closer to mine than to Texas - you typically experience a temp drop at night, unlike down there, which helps. Like trwoolsey said, you may get flower drop, but that won't hurt the plants themselves. Are your plants in the ground, or in pots? Mine are in pots, so these hot days require MUCH more frequent watering.