We went last year on 5th May for two weeks & nearly every day was good for sunbathing, one was overcast if I remember, but great for the time of year.
Evenings a little cooler, but only like a summers eveing here (if its not muggy).
Taken plenty of mozzie repelant.
Olu is a bit of a sun trap anyhow, I went the year before in June & it was hot.