Difficult question to answer. It will probably be sunny (as this corner of the island has the best sunshine records) but we can expect a few showers, often very heavy, at this time of year. We can also expect stormy seas, but at times it can be flat calm and crystal clear.
However, if it does rain at least it will be warm rain. Bring your shorts and T-shirts for daytime and a fleece and jeans for the evenings. A lightweight rain coat is also worth packing in your case.