There are products such as Stay off the Garden, Piss Off etc that you can get from pet shops that will aid in training him not to go on the cobblestones.
What sort of puppy is Patch. Is he cold when he goes out in the rain if so put a coat on him. If he always pees at that time,
try feeding him earlier and only give him a little water in the evening so that he can get used to going earlier or later.
Be consistent, keep training and he will get there, if you want you can try giving him a training pad in the house to use if he does not like storms. I have had dogs for over 30 years and usually find that only 1or 2 in that time do not like going in the rain, but with consistency and lots of praise they can be trained it just takes time.