I try to ride in the evenings.. I estimate how long I'll be out and I go out that amount before sunset.. it doesn't get "dark" until 20 minutes or so after sunset, so it works well for me - it's still plenty light out when the sun hits the horizon. The biggest benefit is that I am NOT a morning person, and it gets significantly cooler as I ride, plus with the sun lower on the horizon, even if the temp is still up there, it doesn't feel as much like it's beating down on you.

It's been plenty hot here though - it's pretty common that it will be at least 105 when I head out, and about 95 when I get home.

Are you wearing a jersey or at least a wicking tee? If not, I'd suggest buying one.. I was *shocked* at how much more comfortable I was - it almost feels as if the breeze just goes right through a jersey, and you don't get soaked in sweat, it is actually able to do it's job of cooling you off (you do get somewhat gritty from salt though)