The Arctic, generally defined as the region north of the Arctic Circle, experiences long, cold winters and cool, short summers. It is a vast area encompassing the Arctic Ocean, adjacent seas, and parts of eight countries, including land with seasonally varying snow and ice cover. While snow is present, the nature of this snowfall and the total amount of precipitation are quite surprising, setting the Arctic apart from many other cold regions of the world.
Understanding Arctic Precipitation Levels
The Arctic is often characterized by extremely low annual precipitation, an unexpected fact given the pervasive ice and snow. Much of the interior Arctic, especially the high-latitude landmasses and the central ice cap regions, receives so little moisture that it is technically classified as a polar desert. This classification applies to areas receiving less than 250 millimeters (about 10 inches) of precipitation annually, which includes both rain and the water equivalent of snow.
The total annual precipitation across most of the Arctic is frequently less than 50 centimeters (20 inches) in snow depth. Coastal Arctic regions, which are moderated by oceanic influences, tend to have warmer temperatures and experience heavier snowfalls than the colder, drier interior areas.
The Atmospheric Science of Low Snowfall
The main reason for the low snowfall in the Arctic is the relationship between temperature and atmospheric moisture. While it can snow even at extremely low temperatures, the air’s capacity to hold water vapor drops sharply as the temperature falls, resulting in very low absolute humidity.
This means that even if the air is fully saturated, the total amount of water available to form precipitation is minimal. Heavy snowfalls usually happen when the air temperature near the ground is relatively mild, typically around -9°C (15°F) or warmer, because warmer air holds significantly more moisture. In the frigid Arctic interior, the air is so cold and dry that the resulting snowfall is light and fluffy, often leading to only light snowfall rates.
Characteristics of Arctic Snow Cover
Once the snow falls, its appearance and behavior are shaped by the Arctic environment. The limited moisture in the atmosphere means that the snow that does fall is typically dry and powdery. The combination of dry snow and persistent high winds leads to frequent blowing snow, which can create the illusion of continuous snowfall even when no new precipitation is occurring.
While the annual snowfall is low, the snow cover is persistent because temperatures rarely rise above freezing for long periods. This persistence allows the snow to accumulate over months or even years, undergoing a process of compaction and recrystallization. The older, denser snow, which has survived at least one melt season, is known as firn, an intermediate stage in the formation of glacial ice.
The snowpack serves as an insulator that protects the underlying permafrost and vegetation from the extreme cold. The bright white surface of the snow also has a high albedo, meaning it reflects a large percentage of solar radiation back into space. This reflective property helps to keep the region cold and regulates the global climate.
How Warming Changes Arctic Snowfall
Warming is rapidly altering the dynamics of precipitation in the Arctic, which is warming three to four times faster than the global average. Warmer air can hold more moisture, meaning that while the Arctic remains cold, the total volume of precipitation is projected to increase significantly. This greater moisture content will not necessarily manifest as more snow, but rather as a shift from snow toward rain.
This transition to a rain-dominated Arctic is projected to happen decades earlier than previously modeled, especially during the autumn season. The increasing frequency of “rain-on-snow” events is an ecological concern, as the rain falls onto an existing snowpack and then freezes. This process creates thick, impenetrable ice crusts that cover the ground, making it difficult for grazing animals like caribou and muskoxen to reach the vegetation below.
The shift from snow to rain also accelerates ice loss, as the rainfall triggers melting and alters the structure of the firn layer on ice sheets. As the Arctic continues to warm and experience more open water due to sea ice loss, the increased moisture from evaporation will continue to drive this transition, fundamentally changing the Arctic landscape and the livelihoods of indigenous communities.