At just over 550 square miles, Kauai offers amazing diversity in it's landscape.  Like the other Hawaiian islands, Kaua'i has a windward and a leeward side.  The tradewinds usually come from the northeast bringing moisture-laden clouds that eventually run into the funnel shaped Mt. Wai'ale'ale where they release their precious raindrops and Kauai's most important source of fresh water.  As the clouds move over the interior of the island, they dry out and by the time they reach the west side of the island, very little rain is left.  This accounts for the north shore being the wettest, greenest, and most lush, while the west side is the driest and most “arid” part of the island.  Don’t expect it to look like a desert though, the west shore is still green!

MICRO CLIMATES

Average day time highs average about 78 in the Winter and 85 in the Summer. Kauai's Mt. Waialeale is in the center of a rain forest (swamp) and is the "wettest spot on Earth," with measured rainfall at over 450 inches a year!  Kauai is the northern most major Hawaiian island and has slightly more rain than the other major islands. The island is remarkably lush and green and is called "The Garden Island."

Like the other islands, more rain falls during the winter months (November through April). The beach areas receive less rain. The trade winds are a great relief because they are light and help blow away much of the humidity. The most popular time to visit is in the summer months.

Kauai actually has seven distinct micro climates including desert-like conditions on the west side, to semi-arid tropical weather at the beach resorts, to cool mountain forests above Waimea Canyon, to pastoral plains on the upper east side to tropical rain forests in the interior. Kauai's location in the northern Pacific, along with its fascinating high mountain formations and the prevailing tradewinds create this unusual spectrum of climate conditions.  The North Shore is more tropical (rainy) and green, while the South Shore (Poipu) has the most sunshine. During the summer months rainfall tends to be very brief, with short bursts followed by sunshine. Kauai's Westside is the warmest and driest (Kekaha, Waimea, and Polihale). 

Ocean surface water temps. are mostly comfortable; ranging from 74 in the Winter (February) to 81 in the summer (late September and October being the warmest). Those scuba diving to lower depths should consider 3-4mm wet-suits.

The following web sites show current weather forecasts and historic weather data (temperature and rainfall maps).

National Weather Service Forecasts

Historic Rainfall and Temperatures