Your weather should be really good. We have gone a few times in March and it was very nice. Not much chance of rain as it is not the rainy season yet, no real humidity to speak of either. If you go to a official weather site you'll see the weather only varies about 5 degrees all year around there. Basically it feels hotter in the summer due to the rainy season and high humditiy.
I believe in March we were mid 80's everyday, slight breeze, accept CC was a lot windier.But that was good, it kept it from getting too hot! It was plenty hot enough to go swimming in the ocean too.
mom x4,grandma x4