The south has a minimum proportion of cloudy days, we in the north have more (that is why we live in a lush vegetation, and not in a desert). The UV-radiation can be high even in the winter, and especially high in the mountains. In summer it is more recommended not to expose your skin for longer periods directly to the Sun between the central 12-15 hours. It is absolutely common for women to sunbathe topless on any of the beaches. Nudism is widely celebrated, there are official sectors on certain beaches. The non-facilitated beaches of course can be easily enjoyed without clothes, only thing you have to be concerned with is not violating the norms of the society.