If it goes north of 100f, or there is high humidity over 90f, I try to ride in the morning or evening. Otherwise, I load up the bike into the back of the trusty Tundra (trucks rule) and head for rides where there are the cooling sea breezes if possible.

For my commute, I take the trusty Tundra if it is going to be over 100f; call me a wimp that's ok. I have ridden home in 102f in jeans and it was not fun. Now I take cycling shorts and a shirt, and change before going home in the heat. I use those arm coolers (yea they help) and I freeze one of my two water bottles, which melts real quick but is better than nothing, to pour on my head.

It's easy to get overheated and get sick, so I take it easy when it's really hot. I take some extra cash to buy water or electrolyte drinks at the minimart and I use routes that pass by parks with shade and bathrooms, so I can duck in and get some water on my Headsweat and shirt. I also pack a small vial of sunscreen to reapply after a good sweat or wetting.