I've found that looking at weather sites doesn't always give an accurate picture.
The weather on the island and the mainland are very different too. We have those nice breezes that tend to blow the rain right on through.
We have had quite a bit of rain lately, but not too many days where it rained all day.
Typically, on the island, we get morning and evening showers but it has been sunny and hot during most of the daytime hours.
Now this morning...it's a little cool....70-ish.....but that is probably a welcome figure for most of you from the states!
Diving is very possible....I've even gone in the rain. I mean your gonna get wet anyway, right?....LOL
You may lose some light and visability, but it's still spectacular!
Bring your books just in case....just not a library.