I think as long as you deep water them the trees will just eventually adjust. I have been observing the city trees that shades my garden. I know it gets deep watered at night by the sprinkler system provided by the city. But with this intense drought, it is just not enough, so the trees are doing a pre-emptive dropping of leaves. Looks like early Fall in my garden now, especially when the higher 90's to triple digits are back. My garden becomes a catch basin for the dried leaves.
Same goes with my other succulents, though some should not go dormant, it seems to go on dormant mode when it is triple digit hot outside, though there are some like the Aeoniums which really naturally go dormant this time of the year. And I also observe them dropping leaves, as the plants try to conserve whatever water/moisture they can get.
Just continue to deep water within the limits permitted. We all have the watering restrictions now statewide..I am just glad majority of my plants are drought tolerant and I have no grass either.
I am just imagining rain right now...have not seen it since mid-March this year.
