I used to do a week @ end of May a lot, but the weather is unpredictable so moved to June! That being said, if it is sunny it gets hot (the sun is 4 weeks shy of being at it's highest point) and sea-temperatures are 21-23c which is swimmable. Hotel swimming pools tend to be a touch warmer. Evenings are mild and not as muggy/humid as in midsummer.
Bars/clubs etc are on the quiet side, which has it's advantages of getting a drink in!
Basically, apart from the warmer sea/pool temps, it's like the south coast of England in July. Take sun-lotion AND a brolly!!