All kinds! But seriously its the rainy season so you could get torrential rain, similarly it could be 26 degrees during the day and almost freezing at night. So, in a nutshell - raingear, warmgear and shorts and T's.
Better yet, bring as little as possible, bring your credit card and buy there. Clothing is cheaper in the US and it would be easier to fit the weather. In general though, it is like gillarosa says ... a little unpredictable!