I bought my wife a Hibiscus plant awhile back. It was thriving well and had great bloomage. We recently moved to the foothills, rise in elevation, slightly higher summer temps (100s+). The leaves have fallen off and there hasn't been any growth. There are green leaf buds on the plant but no growth or flowers. It's watered daily, gets plenty of full direct sun (possibly too much?).
Certified GKH Gardening Expert
The plant is likely trying to acclimate itself, as going from one extreme to another can stress out a plant. While they do enjoy sun, in temps that high you may want to locate the plant in an are with afternoon shade or give it some protection during the hottest part of the day with a shade cloth. A dose of fertilizer, once it's cooled off (don't feed when it's really hot) may help promote growth and subsequent blooming. This article should help: https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-fertilizing.htm