You are certainly hotter with more intense sun then what I have here but we are up in the 90's for a good part of July and August and the vines do great. Why don't you try them in a couple locations? Some in full sun and others protected from the hot afternoon sun and see which does better. The worst that will happen is they won't grow and they are an annual so it's no big deal.
Karyn

Stephanotis / karyn
Hyacinth bean is native to the middle east/north africa. It actually a perennial in its native range and some milder climates. The heat shouldn't really be an issue for it but the sun may burn out the reddish color of the leave and fry the flowers if it gets too hot.

As long as you keep them well watered,and give them some afternoon shade. You should do very well. I grew the white one here in south Fla. in our ungodly heat and humidity last summer. and except for a large attack of aphids right in the middle of the height of the growing period, they did very well.
I had to cut them back several times,and I grew them on top of a hedge to fill it out, and to cover up some ugly parts of the north facing porch. So it was in shade nearly all day. BUT it got over 90 degrees daily and direct sun till noon. Once I watered them well, they took off. When they were dry, they didnt grow at all. Then they took off,once they were watered. They usually grow well in drier soil. but with high heat,I found out they like water! My purple ones didnt grow at all for some reason. The white ones took off and couldnt be stopped, even by the aphids.

I had it last year it was kinda woody vine but the butterflys love the flowers.Not sure if it will come back this year but it was in full sun and did well.