If you travel to Hawaii and look at the maps of the islands and where most of the hotels/resorts are built are on the islands west side. Ever wonder why? 
Trade winds in Hawaii travel from east to west over each of the islands mountains. So the moisture laden tropical winds blowing from east to west loose most of their moisture before getting to the west side of an island.
This is not unique to just Hawaii, this is also the same in most tropical mountainous islands including those in the Caribbean, South Pacific an in the Indian Ocean.













