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" The mountain, 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 1978–2007 the wettest spot in Hawaii is Big Bog on Maui.
The summit of Waialeale features a tropical rainforest climate, with substantial rainfall throughout the course of the year. quotes per year figure as being the 1912–45 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 quotes as the average annual rainfall at Mount Waialeale and claims falls here. Similarly, The Weather Network and the Guinness Book of Weather Records quote 335 days with rain here while suggests that rain falls on 360 days per year. The localtourist industry of Kauai has promoted it as the wettest spot, although the 38-year average at Mawsynram, Meghalaya, India is higher at. Both Mawsynram and Cherrapunji in Meghalaya are recognized by the Guinness Book of World Records as having higher average rainfall. Mawsynram's rainfall is concentrated in the monsoon season, while the rain at Waiʻaleʻale is more evenly distributed through the year.
Causes
Several factors give the summit of Waialeale more potential to create precipitation than the rest of the island chain:
Its northern position relative to the main Hawaiian Islands provides more exposure to frontal systems that bring rain during the winter.
Its peak lies just below the so-called trade windinversion layer of, above which trade-wind-produced clouds cannot rise.
The summit plateau is flanked by steep walled valley's over deep on the three sides most consistently exposed to moisture bearing weather systems. These serve to funnel and concentrate any available precipitable water directly towards the mountain.
The steep cliffs of the mountain's flanks generate intense orthographic lift, causing the moisture-laden air to rise rapidly – over in less than – This combined with the 'barrier' of the trade-wind inversion, serves to very efficiently squeeze almost all of the moisture out of the incoming clouds directly over and immediately downwind of the peak.
Ecology
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 Waiʻaleʻale area is extremely difficult. A number of rare localplant species are named for this mountain, including Astelia waialealae, Melicope waialealae, and the endemicDubautia waialealae.
