Fort Worth commuter. I arrive early and stay at my office a little later and avoid both heat and traffic that way. The sun isn't beating down on you so even if temps are still high, it's not as stressful. My ride home is over an hour with plenty o' hills requiring significant effort. I take 2 large water bottles with icewater and I will stop in the shade a couple of times to gulp on the last 1/3 of the ride. I wear wicking bike clothes and a skullcap under the helmet.
I have a route where the sunrise/sunset doesn't get into a car driver's eyes which would make me virtually invisible on the bike. That was actually a factor when I bought my house - making sure I wasn't driving or biking towards the sun on workdays.
I see very few bike commuters -- it's kind of a shame, as all the evaporative cooling you get on a bike makes it more pleasant than it sounds.