Maui

Maui is the second-largest island in the Hawaiian archipelago, at 727.2 square miles. It is the 17th-largest in the United States. Maui is one of Maui County's four sizable islands, along with Molokai, Lānai, and Kahoolawe.
In 2020, Maui had a population of 168,307, the third-highest of the Hawaiian Islands, behind Oahu and Hawaii Island. Kahului is the largest census-designated place on the island, with a 2020 population of 28,219. It is Maui's commercial and financial hub. Wailuku is the county seat and was the third-largest CDP as of 2010. Other significant populated areas include Kīhei, Lāhainā, and Upcountry Maui, although Lāhainā was mostly destroyed by fire in 2023.
Once part of Maui Nui, Maui is dominated by two volcanic features: Haleakalā in the southeast, and the West Maui Mountains in the northwest. The two are connected by an isthmus about six miles wide that gives the island its nickname, the Valley Isle.
Maui has a significant tourism industry, with nearly three million visitors in 2022. A 2023 report based on 2017 data concluded that nearly 40% of Maui County's economy was tourism-related. Popular tourist destinations include the resorts in the Kāanapali, Kapalua, and Kihei/Wailea/Makena areas; Hāna and the Hana Highway; ʻĪao Valley; Haleakalā National Park; and its many beaches.

Etymology

gives the origin of the island's name in the legend of Hawaiiloa, the navigator credited with discovering the Hawaiian Islands. According to that tradition, Hawaiiloa named the island after his son, who in turn was named for the demigod Māui. Maui's previous name was Ihikapalaumaewa. Maui Island is also called the "Valley Isle" for the large isthmus connecting its northwestern and southeastern volcanic masses.

Geology

Like all other Hawaiian Islands, Maui was formed from the volcanism associated with the Hawaii hotspot.
The islands' volcanic cones are formed from basalt, a dark, iron-rich/silica-poor rock, which poured out of thousands of vents as fluid lava over millions of years. Some of its volcanoes were close enough to each other that lava flows on their flanks overlapped, merging into a single island. Maui is one such "volcanic doublet," formed from two shield volcanoes that overlapped to form Maui.
The older, western volcano has eroded considerably, forming the peaks of the West Maui Mountains. Puʻu Kukui is the highest, at. The larger, younger volcano to the east, Haleakalā, rises to above sea level, and measures from seafloor to summit. The eastern flanks of both volcanoes are cut by deeply incised valleys and steep-sided ravines that run downslope to the rocky, windswept shoreline. The isthmus was formed by sandy erosional deposits.
Maui's last eruption likely occurred between 1480 and 1600; the resulting lava flows are located at Cape Kīnau between Āhihi Bay and La Perouse Bay. Haleakalā is dormant, but not extinct.
Maui is part of a much larger unit, Maui Nui, that includes the islands of Lānaʻi, Kahoʻolawe, Molokaʻi, and the now submerged Penguin Bank. During periods of reduced sea level, including as recently as 200,000 years ago, the channels between them become exposed and join the island into a single landmass.

Climate

The climate is characterized by a two-season year, tropical and uniform temperatures at any given elevation, geographic differences in rainfall, high relative humidity, extensive cloud formations, and dominant trade wind flow.
Maui has a range of climatic conditions and weather patterns:

Half of the land is within of the coast, creating a strong marine influence.
Macro weather patterns are typically determined by elevation and orientation towards the trade winds.
Maui's rugged, irregular topography drives variations in conditions. Air swept inland on the trade winds is redirected by the mountains, valleys, and vast open slopes. This three-dimensional flow of air produces variations in wind speed, cloud formation, and rainfall.

Maui displays diverse climatic conditions, each of which is specific to a sub-region. These sub-regions are defined by major physiographic features and by location on the windward or leeward side.
Maui's daytime temperatures average between and year round, while evening temperatures are about cooler in the more humid windward areas, about cooler in the drier leeward areas, and cooler still in higher elevations.
An exception to the normal pattern is the occasional winter Kona storm that brings rainfall to the South and West areas accompanied by high southwesterly winds.

Microclimates

Maui has examples of all microclimates, each typical to specific locations.

Windward lowlands – Below on north-to-northeast sides. Roughly perpendicular to the trade winds. Moderately rainy; frequent trade wind-induced showers. Skies are often cloudy to partly cloudy. Air temperatures are relatively more uniform.
Leeward lowlands – Daytime temperatures are higher and nighttime temperatures are lower than in windward locations. Dry weather is prevalent, except for sporadic showers that drift over the mountains to windward and during short-duration storms.
Interior lowlands – Intermediate conditions, often sharing characteristics of other lowland sub-regions. Occasional intense afternoon showers from clouds that form due to local daytime heating.
Leeward side high-altitude mountain slopes with high rainfall – Extensive cloud cover and rainfall all year long. Mild temperatures are prevalent, but humidity is higher than in any other sub-region.
Leeward side lower mountain slopes – Rainfall is higher than on leeward lowlands but much less than at similar altitudes on the windward side; however, maximum rainfall usually occurs leeward of the crests of lower mountains. Temperatures are higher than on the rainy slopes of the windward sides of mountains; cloud cover is almost as extensive.
High mountains – Above about on Haleakalā, rainfall decreases rapidly with elevation. Relative humidity may be ten percent or less. The state's lowest temperatures are experienced in this region: air temperatures below freezing are common.

These microclimates help to define the major regions: Central Maui; leeward South Maui and West Maui; windward North Shore and East Maui; and Upcountry.

Central Maui consists primarily of Kahului and Wailuku, and occupies the flat isthmus between the West Maui Mountains and Haleakalā. Kahului is the center of the island and tends to keep steady, high temperatures throughout the year. The Kahului microclimate can be muggy, but usually feels relatively dry and is often breezy. The Wailuku area is closer to the West Maui Mountain range. There, rainfall is greater throughout the year and humidity is higher.
South Maui and West Maui are both on the leeward side. These areas are typically drier, with higher daytime temperatures, and the least amount of rainfall.

File:Waianapanapa_State_Park_Maui_Hawaii_Road_to_Hana_.jpg|right|thumb|Waianapanapa State Park in East Maui, next to Hana

The North Shore and East Maui are both on the windward side. Facing the prevailing, northeast trade winds, these areas have heavier rainfall levels, which increase considerably at higher elevations.
Upcountry Maui is the name for the sloping area on the western face of Haleakalā, including the towns of Makawao, Pukalani, and Kula. This area ranges from to, and the climate tends toward mild heat during the day and cool evenings. The higher the elevation, the cooler the evenings: during Maui's winter, Upper Kula can be as cold as in the early morning hours and the Haleakalā summit can dip below freezing and become covered in snow.
Rainfall

Showers are common; while some of these are heavy, the majority are light and brief. Thunder and lightning are rare, even during intense storms. Throughout the lowlands, summer trade winds produce a drier season. Annual rainfall averages in leeward coastal areas, such as the shoreline from Maalaea Bay to Kaupo. At the other extreme, the average exceeds along the lower windward slopes of Haleakalā, particularly along Hāna Highway. Big Bog, a spot on the edge of Haleakalā National Park overlooking Hana at about elevation had an estimated mean annual rainfall of over the 30-year period of 1978 to 2007. If the islands of Hawaii did not exist, the average annual rainfall on the same patch of water would be about. Instead, the mountainous topography induces an average of about.In the lowlands, rainfall is most likely to occur during night or morning hours, and least likely in mid-afternoon. The most pronounced daily variations in rainfall occur during the summer because summer rainfall generally consists of night-time trade wind showers. Winter rainfall in the lowlands is the result of storm activity, which is as likely to occur in the daytime as at night. Rainfall variability is far greater during the winter when occasional storms contribute appreciably to rainfall totals. Such wide swings in rainfall produce occasional droughts, sometimes causing economic losses. These occur when winter rains fail to produce sufficient significant rain, impacting normally dry areas outside the trade winds that depend on them the most. The winter of 2011–2012 produced extreme drought on the leeward sides Maui, and some other islands.

Natural history

Maui is home to a large rainforest on the northeastern flanks of Haleakalā, which serves as the drainage basin for that side.
Maui is home to many coral reefs. However, many have been damaged by pollution, run-off, and tourism, although sea turtles, dolphins, and Hawaii's tropical fish remain abundant. Leeward Maui once had a dry cloud forest, but this was destroyed by human activities over the last three hundred years.

Wildlife

Maui is the leading whale-watching center in the Hawaiian Islands for the humpback whales who winter in Maui County's sheltered Auau Channel. These mammals migrate approximately from Alaskan waters each autumn and spend November–April mating and birthing in the warm waters. They are typically sighted in pods: small groups of several adults, or groups of a mother, her calf, and a few suitors. Humpbacks are an endangered species protected by U.S. federal and Hawaii state law. An estimated 21,000-26,000 humpbacks live in North Pacific waters. Although they face many dangers, due to pollution, commercial vessels, and military sonar testing, their numbers have increased rapidly in recent years, estimated at 7% growth per year.
Birdlife lacks the concentration of endemic species found in some other Hawaiian islands. As recently as 200,000 years ago Maui was part of Maui Nui, thus reducing the odds that birds or other species would be endemic to any single one of these. Although Molokai had several endemic bird species, in modern times Maui Nui's other islands host little endemic birdlife. During and after the Maui Nui period, Maui hosted a species of moa-nalo, a species of harrier, an undescribed sea eagle, and three species of ground-dwelling flightless ibis, plus other species. Today, Maui's most notable surviving endemic birds are probably the ʻAkohekohe and the Maui parrotbill, also known as Kiwikiu, both of which are critically endangered and only found in an alpine forest on the windward slopes of Haleakalā.
Conservation efforts have examined how to mitigate female parrotbill mortality since that is a key driving factor driving population decline. The parrotbill lacks resistance to mosquito-born diseases, particularly avian malaria, so only forests above 1500 meters of elevation provide refuge. The habitat was undergoing restoration in east Maui as of 2018. As Maui's human population grew, previously undeveloped areas that provided a refuge decreased in size. More than 250 species of local flora are federally listed as endangered or threatened. Birds found on other islands as well as Maui include the ʻIʻiwi, Hawaiʻi ʻAmakihi,'' as Maui ʻAlauahio well as the Nene, Hawaiian coot, Hawaiian stilt.
In 2024, Haleakalā National Park began to employ the incompatible insect technique to reduce the park's mosquito population.
Maui is also home to the Hawaiian hoary bat, Hawaii's only native terrestrial mammal. Marine mammals notably include spinner, bottlenose, and spotted dolphins.