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The term “extreme cold” can have varying definitions in hazard identification. Further, what is considered an extreme cold event will vary greater by region. Generally, extreme cold events refer to a prolonged period (days) with extremely cold temperatures, which may or may not be associated with a winter storm. Temperatures near or below freezing in Maui’s generally year-round warm and mild weather regions can have health risks to vulnerable populations, as well as economic impacts.
Hypothermia is an extreme cold-related impact that result when individuals are exposed to extreme temperatures. Hypothermia occurs when the body begins to lose heat faster than it can produce it. As a result, the body’s temperature begins to fall. If an individual’s body temperature falls below 95°F, then hypothermia has set in and immediate medical attention should be sought. Hypothermia is characterized by uncontrollable shivering, memory loss, disorientation, incoherence, slurred speech, drowsiness and exhaustion. Left untreated, hypothermia will lead to death. Hypothermia occurs most commonly at very cold temperatures but can occur at cool temperatures (above 40°F) if an individual isn’t properly clothed or becomes chilled.
Nearly the entire United States is susceptible to extreme cold events. The degree of exposure typically depends on the normal expected severity of local winter weather. Given the atmospheric nature of the hazard, the entire county may experience extreme cold events, but higher elevations, such as Haleakalā summit, are more likely to experience extreme cold.
Due to wind patterns and changing topography, average temperatures across Maui County and its many microclimates can vary widely. As taken from a monitoring station at Kahului Airport in central Maui, average low temperatures range from the low 60s in the winter months to the low 70s in the summer months. Record lows were c older, ranging from the upper - 40s in the winter months to around 60 degrees in the summer months. It should be noted that average and extreme low temperatures at higher elevations within the County can be much cooler. For instance, temperatures at Haleakalā summit can regularly dip below freezing.
Past extreme cold events were gleaned from the NCEI Storm Events Database, which reported one historic extreme cold event in Maui County occurring in 2005 (reported as a high wind event). During this event, icy conditions on Haleakalā caused power outages and interruptions to broadcasting. Further, according to Maui County officials, Haleakalā received snow in 2019 and in 2020, and winter weather advisories were issued for Haleakalā in December 2016, December 2017, and February 2018 for snow, freezing rain, and icy roads at elevations above 9,000 feet. In addition, during the 2019 snow event, snow fell at Polipoli State Park on the slope of Haleakalā (6,200 feet elevation), which is possibly the lowest elevation record of snowfall in Hawai’i. During Kona storms, blizzard conditions are possible on Haleakalā. It is also expected that the county has experienced extreme cold events that have gone unreported, especially those events which did not result in injuries or damages.
The extent of extreme cold or freeze events can be measured in terms of record low temperatures. The lowest temperature reported from the Western Regional Climate Center at the Kahului Airport was 48°F, occurring in January of 1969. However, the lowest temperature recorded at Haleakalā summit was 15°F. Lower temperatures are possible.
Extent of extreme cold can also be measured in terms of loss of human and animal life, or by economic costs imposed by property and infrastructure loss. No extreme cold impacts have been reported by the Maui County officials. Therefore, it is unlikely that an extreme cold event would cause significant property damage in the county
Future Probability
The frequency of extreme cold events is projected to decline in the future due to overall warming trends associated with climate change. Community planning areas with higher elevations are more likely to experience extreme cold events than those at lower elevations, such as central valley areas.
It can be assumed that all existing and future buildings, infrastructure, and populations are at risk to the earthquake hazard. There are several factors that impact vulnerability to earthquake in Maui County.
An earthquake could result in deaths, injuries, property damage, environmental damage and disruption of normal services and business activities. The effects could be aggravated by collateral emergencies such as fires, flooding, tsunamis, landslides, hazardous material spills, utility disruptions, and transportation emergencies. Aftershocks to major earthquakes could also be large enough to cause damage.
Buildings and Infrastructure: All structures, including critical facilities, are at risk to extreme cold events. Temperatures dipping below freezing may cause damage to structures, such as burst pipes, although temperatures in most areas of the county are rarely low enough to freeze pipes. Structure fires are also more common during extreme cold events, as alternative or unsafe heating sources are more likely to be employed (i.e., woodfires, space heaters).
Health and Safety: All populations in Maui County are considered at risk to extreme cold events. While unlikely in most areas of Maui County, extreme cold can result in frostbite or hypothermia. Certain populations, such as the elderly, young children, and those without access to an adequate heat source are considered at a higher risk to the impacts of extreme cold. Evacuations are not likely for extreme cold events. In summit areas, winter storm or wind chill warnings may be issued in association with extreme cold events. At elevations below 6,000 feet, a freeze warning is issued if temperatures drop below freezing.
Wide-scale impacts to public health from extreme cold/wind chill events are limited. Carbon monoxide- related deaths are highest during extreme cold events, due to the increased use of gas-powered furnaces and alternative heating sources (e.g., generators, grills, and camp stoves) inside homes and buildings. Risk for fire and electric shock is also increases when using alternative heating and power sources, such as space heaters.
Economic Impacts: Economic impacts of extreme cold events in Maui County and limited. Losses due to decreased tourist activity during extreme cold events (such as beach-going, water sports, and boating) may occur. Further, extreme cold temperatures may result in losses to agriculture or landscaping.
Climate Change Impacts: Extreme cold and freeze events are projected to become less frequent and less intense in Maui County as temperatures increase. According to the Fourth National Climate Assessment, annual average temperatures in Hawai’i will increase by 2-3°F by the mid-21st century and 5-6°F by the late-21st century under a high emissions scenario (representative concentration pathway (RCP) 8.5). RCP 8.5 is a scenario in which emissions continue to rise sharply through 2050 and plateau around 2100.
However, an increase in intense storms may result in increased snowfall events at Maui County’s higher elevations, as observed in recent years. When it snows on Haleakalā, traffic jams are caused up the mountain as people travel to see it. Further, it is unknown if climate change will cause increases in Kona storm frequency and intensity, which can bring blizzard-like conditions to high elevations.
