I imagine its not too different to July (early July) when I went and it was lovely. Its a really nice resort, we really enjoyed it there.
Costa Dorada more to the north of Spain than the other costas so it can be more of an average European weather outlook - it can be a bit overcast, but the sun comes out eventually. We went a number of years ago in June and it was very overcast until at least late morning. More towards the middle of summer would have been better.