Lots of good advice. I ride early in the morning also. C'mon down to Tucson where it's still 65 degrees at 6AM!

When it's really hot, I use a Camelback. I put it in the fridge the night before so it's nice & cold. I might add a couple of ice cubes, depending on how hot it's going to be. I also dedicate at least one water bottle to an electrolyte replacement drink.

I like to really hydrate the day before a long hot ride, so I'm starting out on a positive side.

Light colored, breathable jerseys are essential. Note that the heat on your bare skin might feel hotter than the heat on a jersey, so you might want to save the cute little spaghetti strap tops for the gym. (That's what I do )