The Hawaiian Islands have one of the most consistent climates on earth.  The average Winter Temperature is 72 degrees.  The average Summer Temperature is 78 degrees. 

The trade winds primarily blow from the northeast.  As the trade winds blow, they come across the Pacific rising up the slopes of Mt. Wai'ale'ale to an elevation of 5,148.  The moist air is cooled, condensed and rain results.  Mt. Wai'ale'ale is one of the wettest places on earth...with an average of over 450 inches of rain per year.

On Kauai, the north shore benefits from the abundance of rain.  One the south and west slopes of Kauai, there is a rain shadow where few clouds and little rain falls. 

Wherever you are on the island, the weather is pleasant, and showers are only there to create Hawaii's beautiful trademark rainbows.  Look for them especially in the mornings and evenings, but any time you see a rain shower pass by.