Is it normal for a Sweet Acacia desert tree in Arizona in 110 degree heat shed in June?
Certified GKH Gardening Expert
The premature leaf drop is most likely due to the extreme heat.
Shade cloths can be used to help reduce the stress to trees and shrubs, but if the tree is large, this is not possible.
Give the tree additional water with a slow and deep watering.
Hopefully the temps will drop and the trees can recover.