Well, Hi, there, Diane. I'm Melissa from the Yahoo group. Glad to welcome you!
Wow, that's HOT!! I've seen 39 degree heat and every degree at that 'elevation' is more torture! I think you should try growing arabicums, rather than the usual obesums. OK, in plain English, arabicums are from Arabia, and can take a lot more heat than most other Adeniums. I forgot to bring in two trays of seedlings once. They were covered with plastic, and boiled in 36 degree (97f) sun on my deck. Poor things! The obesums melted, really, but the arabicums were just fine.
That book is super wonderful, isn't it? I still spend time reading even though I have it memorized by now.
So, how ccccccold does it get in Adelaide?