What could be affecting leaves of plants across my garden?

Over the past couple of weeks I have noticed trees, shrubs and many flowers increasingly affected by discoloured leaves. A Rowan tree is badly affected. This is the first time beyond roses that I've seen such discolouration of leaves. A few photos are included. Anyone have any ideas as to the cause? Thanks.

 

Some of the damage could be from hail stones. I think one plant, No 4 may have powdery mildew which could be from very wet conditions going into warm weather. I am sure there experts on here who will be able to be more helpful None of the damaged plants seem to be ailing which is good.

 

My guess was going going to be hail as well.
It appears to be on far too many different types of plants to be disease or even insect attack.

 

I was also going to suggest hail.
It's very unlikely to be a disease or pest affecting plants of so many different types. Hailstorms can be very brief and localised so if you were out at the time (or even indoors) you might not have noticed it.

 

Another one here for hail damage for most of it. Healthy plants will grow out of it.