Agree with Cheryl, I would provide some shade and step up watering. If all of them are rooted and leafing properly already, it will not mind daily watering especially when our temps are going always beyond 100F for several days. I have to do that to my Plumerias, in fact I even spray the entire stem, it dries out too fast anyways. Our humidity is so low...it needs all the humidity it can try to have. I water early in the day before the sun hits them, direct to the root zone. It loves water when temps are very hot. My plumerias thankfully get the shade of our city trees, so it helps a lot during heat wave days.
Have seen them growing so well in my old homeland and we get over 22 typhoons there. The consistent thing that they have there too is high temps and high humidity. So don't be afraid to water them more during summer and during heat wave.
