In the south east we had 6% of the normal rain in June and upto local thunderstorms on 26/27/28th July only 1% in July.
Currently it is the young and semi mature trees, especially newly planted trees, that are suffering most, due to their smaller root systems. Whereas mature trees have much larger and deeper root systems, combined with the decent rain we had earlier in the year, as at present (we believe) meant that water tables have not dropped. This may change and water tables drop.
We urge you to water every small and semi mature trees daily at present,even if they are in the pavement outside your property.
For trees and shrubs in containers, they should be being watered 1-2 times a day and ideally moved into the shade.
If trees are losing leaves, this is both a natural response and a cause for concern. In very hot/dry weather, trees will lose less important leaves to reduce transpiration / water loss. They could even drop all leaves. These trees should also be watered.