Mount Waialeale () is a shield volcano and the second highest point on the island of Kauai in the Hawaiian Islands. Its name literally means "rippling water" or "overflowing water".
Mount Waialeale, at an elevation of , averages more than of rain a year since 1912, with a record in 1982; its summit is one of the rainiest spots on earth. However, recent reports mention that over the period 1978âÂÂ2007 the wettest spot in Hawaii is Big Bog on Maui ( per year).
The summit of Waialeale features a tropical rainforest climate (Köppen Af), with substantial rainfall throughout the course of the year. quotes per year figure as being the 1912âÂÂ45 average, an average that quite possibly will have changed since then, while The National Climatic Data Center quotes this figure as a 30-year average. The Weather Network and The Guinness Book of Weather Records quotes rain per year, while Meteorology Today quotes as the average annual rainfall at Mount Waialeale and De Wereld van het Weer claims falls here. Similarly, The Weather Network and the Guinness Book of Weather Records quote 335 days with rain here, while Weird Weather suggests that rain falls on 360 days per year.
The local tourist industry of Kauai has promoted it as one of the wettest places on earth, which it is. The rainfall at Waiûaleûale is evenly distributed through the year.
Several factors give the summit of Waialeale more potential to create precipitation than the rest of the island chain:
The great rainfall in the area produces the Alakai Wilderness Preserve, a large boggy area that is home to many rare plants. The ground is so wet that although trails exist, access by foot to the Waiûaleûale area is extremely difficult.
A number of rare local plant species are named for this mountain, including Astelia waialealae, Melicope waialealae, and the endemic Dubautia waialealae.