I feel your pain Bob.
The worst part about riding in those temperatures is from the radiant heat through the road as the bitumen acts as a heat sink during the day. It's like riding though a furnace and that is probably the best way I can describe it. If you use a ventilated jacket, it just sends that heat over your body and the last thing you need is to have all the sweat your body produces being wicked away by the airflow. Dehydration soon follows.
Trying to explain to someone from a cooler climate about keeping out of the heat and regularly consuming water and electrolytes is sometimes like talking to a brick wall. By the time dehydration and heat stress turn into heat stroke, then it is too late and can be fatal.
A good decision.