Hawai’i has experienced rapid warming, especially since the mid-1970s. Its air temperature trend has diverged from the Pacific Decadal Oscillation (PDO) as well as local sea surface temperature trends, perhaps signaling increasing influence of global warming [1]. Drought, although it rarely affects an entire island at one time, may occur when there are either no winter storms or no trade winds. If there are no winter storms, the normally dry leeward areas are most impacted. A dry winter, followed by a normally dry summer and another dry winter, can have serious effects. The absence of trade winds affects mostly the windward and upland regions, which receive a smaller proportion of their rain from winter storms [4]. Hawai’i’s climate is likely to continue to become drier as warming continues. Reduced precipitation in combination with a possible increase in potential evapotranspiration due to increased temperature would result in significant reductions in ground-water recharge and stream discharge, and would severely impact vulnerable high-elevation ecosystems [1]. Hawai’i State has a multi-hazard mitigation plan that addresses climate-related hazard risks, as well as considers some of the impacts from future climate change, such as sea level rise and more frequent extremes. Most major disaster declarations for Hawa’i are based on climate-related hazards that total billions of dollars in damages [7]. Even the earthquake disaster in 2006 damaged irrigation infrastructure and reservoirs that created extensive drought-related problems during the ENSO event that followed in 2007 [7]. Each of the four counties has its own mitigation plan that address localized risks. The plans recommend hazard mitigation actions, similar to climate change adaptation strategies, to build resilience [7].
The Hawaiian Islands cover 10,932 square miles (28,314 square km) of which 6,423 sq miles (16,635 sq km) is land area and 4,508 sq miles (11,676 sq km) is water, mainly the Pacific Ocean [7]. The Hawaiian archipelago is the world’s longest island chain (1,523 miles or 2,451 kilometers), composed of 132 islands with eight main islands [7], including Niʻihau, Kauaʻi, Oʻahu, Molokaʻi, Lanaʻi, Kahoʻolawe, Maui, and Hawaiʻi. All the main islands are inhabited except Kahoʻolawe. Hawaiʻi Island (also known as Big Island) is the largest island with an area of 4,028 sq miles (10,434 sq km). Oʻahu, the most highly populated island, has an area of 598 sq miles (1,548 sq km) [10]. The main islands are separated into four counties: the County of Kaua‘i, including Ni‘ihau; the City and County of Honolulu (the island of O‘ahu); the County of Maui, including Maui, Molokaʻi, and Lanaʻi; and the County of Hawaiʻi (the island of Hawaiʻi) [10]. The highest point in the Hawaiian Islands is Mauna Kea on the island of Hawaiʻi, which reaches 13,796 feet (4,205 meters) [10]. The Big Island also contains active volcanoes along the southern edge of the island, which are actually causing the island to slowly get bigger [8].
Climate
Hawaiʻi has a tropical climate with near-constant trade winds blowing from the east. Hawaiʻi has two seasons: the dry season from May to October, and the wet season from October to April. Summer highs are usually in the upper 80s°F (around 31°C) during the day, and mid 70s (around 24 °C) at night. Winter temperatures during the day are usually in the low to mid 80s, (around 28 °C) and (at low elevation) seldom going below the mid 60s (18 °C) at night [7]. While Hawaiʻi’s climate is equable, the mountainous topography makes it one of the most spatially diverse regions on earth. Hawai‘i has various ecosystems ranging from deserts to tropical rain forest and even frozen alpine tundra, all in close proximity [4]. Snow, not usually associated with tropics, falls at the higher elevations of Mauna Kea and Mauna Loa on the Big Island in some winter months [8]. Local climates vary considerably on each island, generally divisible into windward and leeward areas based upon location relative to the higher mountains. Windward sides face the Northeast Trades and receive much more rainfall; leeward sides are drier and sunnier, with less rain and less cloud cover [8]. Variations in rainfall on the Hawaiian Islands are dramatic. At one extreme, the annual rainfall on the west (leeward) side of Hawaiʻi Island averages 20 inches. At the other extreme, the annual average along the lower windward slopes of Haleakala on Maui exceeds 300 inches (7,620mm) [2]. Mount Waiʻaleʻale on Kauaʻi, which is notable for rainfall, has the second highest average annual rainfall on Earth, about 460 inches (38 ft. 4 in., or 11.7 m) [8]. Although hurricanes and tsunamis are a rare occurrence in Hawaiʻi, all the main islands have been affected at some point. Tsunamis have accounted for more lost lives than all other local disasters combined [6].
Hawaiʻi
State of Hawai’i, USA
Hawai’i has experienced rapid warming, especially since the mid-1970s. Its air temperature trend has diverged from the Pacific Decadal Oscillation (PDO) as well as local sea surface temperature trends, perhaps signaling increasing influence of global warming [1]. Drought, although it rarely affects an entire island at one time, may occur when there are either no winter storms or no trade winds. If there are no winter storms, the normally dry leeward areas are most impacted. A dry winter, followed by a normally dry summer and another dry winter, can have serious effects. The absence of trade winds affects mostly the windward and upland regions, which receive a smaller proportion of their rain from winter storms [4]. Hawai’i’s climate is likely to continue to become drier as warming continues. Reduced precipitation in combination with a possible increase in potential evapotranspiration due to increased temperature would result in significant reductions in ground-water recharge and stream discharge, and would severely impact vulnerable high-elevation ecosystems [1]. Hawai’i State has a multi-hazard mitigation plan that addresses climate-related hazard risks, as well as considers some of the impacts from future climate change, such as sea level rise and more frequent extremes. Most major disaster declarations for Hawa’i are based on climate-related hazards that total billions of dollars in damages [7]. Even the earthquake disaster in 2006 damaged irrigation infrastructure and reservoirs that created extensive drought-related problems during the ENSO event that followed in 2007 [7]. Each of the four counties has its own mitigation plan that address localized risks. The plans recommend hazard mitigation actions, similar to climate change adaptation strategies, to build resilience [7].
Geography
The Hawaiian Islands cover 10,932 square miles (28,314 square km) of which 6,423 sq miles (16,635 sq km) is land area and 4,508 sq miles (11,676 sq km) is water, mainly the Pacific Ocean [7]. The Hawaiian archipelago is the world’s longest island chain (1,523 miles or 2,451 kilometers), composed of 132 islands with eight main islands [7], including Niʻihau, Kauaʻi, Oʻahu, Molokaʻi, Lanaʻi, Kahoʻolawe, Maui, and Hawaiʻi. All the main islands are inhabited except Kahoʻolawe. Hawaiʻi Island (also known as Big Island) is the largest island with an area of 4,028 sq miles (10,434 sq km). Oʻahu, the most highly populated island, has an area of 598 sq miles (1,548 sq km) [10]. The main islands are separated into four counties: the County of Kaua‘i, including Ni‘ihau; the City and County of Honolulu (the island of O‘ahu); the County of Maui, including Maui, Molokaʻi, and Lanaʻi; and the County of Hawaiʻi (the island of Hawaiʻi) [10]. The highest point in the Hawaiian Islands is Mauna Kea on the island of Hawaiʻi, which reaches 13,796 feet (4,205 meters) [10]. The Big Island also contains active volcanoes along the southern edge of the island, which are actually causing the island to slowly get bigger [8].
Climate
Hawaiʻi has a tropical climate with near-constant trade winds blowing from the east. Hawaiʻi has two seasons: the dry season from May to October, and the wet season from October to April. Summer highs are usually in the upper 80s°F (around 31°C) during the day, and mid 70s (around 24 °C) at night. Winter temperatures during the day are usually in the low to mid 80s, (around 28 °C) and (at low elevation) seldom going below the mid 60s (18 °C) at night [7]. While Hawaiʻi’s climate is equable, the mountainous topography makes it one of the most spatially diverse regions on earth. Hawai‘i has various ecosystems ranging from deserts to tropical rain forest and even frozen alpine tundra, all in close proximity [4]. Snow, not usually associated with tropics, falls at the higher elevations of Mauna Kea and Mauna Loa on the Big Island in some winter months [8]. Local climates vary considerably on each island, generally divisible into windward and leeward areas based upon location relative to the higher mountains. Windward sides face the Northeast Trades and receive much more rainfall; leeward sides are drier and sunnier, with less rain and less cloud cover [8]. Variations in rainfall on the Hawaiian Islands are dramatic. At one extreme, the annual rainfall on the west (leeward) side of Hawaiʻi Island averages 20 inches. At the other extreme, the annual average along the lower windward slopes of Haleakala on Maui exceeds 300 inches (7,620mm) [2]. Mount Waiʻaleʻale on Kauaʻi, which is notable for rainfall, has the second highest average annual rainfall on Earth, about 460 inches (38 ft. 4 in., or 11.7 m) [8]. Although hurricanes and tsunamis are a rare occurrence in Hawaiʻi, all the main islands have been affected at some point. Tsunamis have accounted for more lost lives than all other local disasters combined [6].
Related Links Monthly Precipitation Summary from NOAA/NWS Weather Forecast Office Honolulu Latest Seasonal Rainfall Forecast for Hawaii from NOAA’s Climate Prediction Center (CPC) Tropical Pacific Islands Rainfall Outlooks (CPC) El Niño and its Impacts on The Hawaiian Islands Hawaiʻi Climate Data PortalHawaiʻi Mesonet References [1] Giambelluca, T. W., H. F. Diaz, and M. S. A. Luke (2008), Secular temperature changes in Hawai‘i, Geophysical Research Letters, 35, L12702, doi:10.1029/ 2008GL034377. [2] Best Places Hawaii, http://www.bestplaceshawaii.com/tips/weather/, accessed May 5, 2021. [3] City Data: Hawaii Economy, http://www.city-data.com/states/Hawaii-Economy.html , accessed September 13, 2012. [4] S.P. Juvik and J.O. Juvik. (Eds.) 1998. Atlas of Hawai‘i (3rd Ed.). Honolulu: University of Hawai‘i Press. [5] National Climatic Data Center (NCDC), National Oceanic and Atmospheric Administration. [6] Pacific Disaster Center, http://www.pdc.org/iweb/tsunami_history.jsp, accessed September 13, 2012. [7] State of Hawai‘i 2018 Hazard Mitigation Plan, accessed May 5, 2021. [8] Wikipedia, Hawaii, http://en.wikipedia.org/wiki/Hawaii, accessed September 13, 2012.
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