At the moment, you see people diving in anything from 3mm shorties to drysuits. I personally am wearing a 7mm with a 3mm hood and vest. The water temperature is 22C at the divesites around Sharm. It depends on you and what you are used to. I should imagine that in june i will have discarded the hood and vest. And we do mostly 1 hour dives, air permitting. Even with my current set up I get chilled to the bone by the end of the 3rd dive.