The Weather is largely mild almost throughout the year. You will be able to travel almost throughout the year. Here is a rough guide so you can decide the time most suitable to your visit.
Winter (November to Feb): The weather is cold so the beaches will not have the same dreamy effect. In fact a lot of the places will be closed in winter. But you will get a tranquil if mild beach holiday without any crowds. You can always visit the museums during this time.
Rain: March and April See rain and it is quite unpredictable. However the tariffs are cheaper and if you are lucky you may not see any rain almost throughout your visit.
Summer: June to August is summer. This is the peak tourist season. Lots of crowd, parties, dancing, activity and event but also peak season rates should be expected. If you want a milder version of this September and October are probably the best time to visit because it isn’t too cold nor are there many people, a win-win.