Mauna Kea, a dormant volcano on the Big Island of Hawaiʻi, is the highest point in the state. While Hawaiʻi is known for warm, tropical beaches, this mountain’s extreme elevation creates a unique environment. The summit frequently receives snowfall, transforming the volcanic landscape into an unexpected winter scene. This striking contrast, where tropical warmth meets alpine conditions, sets the stage for the specific weather patterns needed for snow to occur.
The Primary Snow Season
Snowfall on Mauna Kea primarily occurs during the Northern Hemisphere winter, generally between December and March. This period aligns with the Hawaiian Islands’ wet season, which brings the necessary moisture to the high elevations. While the summit’s cold temperatures are consistent, precipitation is often intermittent and relies on specific storm systems.
Snow is not a daily occurrence, and frequency varies significantly depending on Pacific weather patterns. Occasional snowfall can begin as early as October and sometimes extend into April or May. The mountain regularly sees at least one snow event annually, though the accumulation is not guaranteed to be substantial.
Meteorological Conditions Required
The primary factor enabling snow is Mauna Kea’s towering height, which reaches nearly 14,000 feet above sea level. This elevation places the summit into the atmosphere’s colder layers, where temperatures consistently drop below freezing. Winter temperatures at the summit generally range from 25 to 40 degrees Fahrenheit, creating the necessary cold air mass.
For snow to fall, cold temperatures must combine with a sufficient source of moisture, often supplied by a mid-latitude storm system known as a Kona Low. These low-pressure cells typically form west of Hawaiʻi and bring heavy rain and strong winds. The Kona Low is crucial because it pushes the freezing level down the mountain and directs moisture toward the high peaks, allowing precipitation to fall as snow rather than rain.
This combination of extreme altitude and the passage of a Kona Low or similar cold front is necessary for a snowfall event. Without the cold air mass bringing moisture and lowering the freezing isotherm, the mountain remains cold but dry. The snowline typically remains high, usually only reaching below 9,000 feet during the most intense winter storms.
Snowfall Duration and Accumulation
Most snowfall events on Mauna Kea result in a light dusting, often measuring only a few inches. Due to the mountain’s latitude and high solar intensity above the clouds, this snow melts quickly, sometimes lasting only a few hours or a day. The snow texture can become icy after exposure to the intense sun.
Heavy accumulations are rare but occur during major storm systems, such as the two-foot-plus event seen in 2016. When such storms occur, the snow can persist for a few days to a week before melting completely. The estimated annual average snowfall is low, around 7.41 inches, illustrating that while snow is regular, it is typically fleeting.