Climate of the Arctic

The climate of the Arctic is characterized by long, cold winters and short, cool summers. There is a large amount of variability in climate across the Arctic, but all regions experience extremes of solar radiation in both summer and winter. Some parts of the Arctic are covered by ice (sea ice, glacial ice, or snow) year-round, and nearly all parts of the Arctic experience long periods with some form of ice on the surface. Average January temperatures range from about −34 °C to 0 °C (−40 to +32 °F), and winter temperatures can drop below −50 °C (−58 °F) over large parts of the Arctic. Average July temperatures range from about −10 to +10 °C (14 to 50 °F), with some land areas occasionally exceeding 30 °C (86 °F) in summer.

The Arctic consists of ocean that is largely surrounded by land. As such, the climate of much of the Arctic is moderated by the ocean water, which can never have a temperature below −2 °C (28 °F). In winter, this relatively warm water, even though covered by the polar ice pack, keeps the North Pole from being the coldest place in the Northern Hemisphere, and it is also part of the reason that Antarctica is so much colder than the Arctic. In summer, the presence of the nearby water keeps coastal areas from warming as much as they might otherwise.

There are different definitions of the Arctic. The most widely used definition, the area north of the Arctic Circle, where, on the June solstice, the sun does not set is used in astronomical and some geographical contexts. However, in a context of climate, the two most widely used definitions in this context are the area north of the northern tree line, and the area in which the average temperature of the warmest month is less than 10 °C (50 °F), which are nearly coincident over most land areas (NSIDC).

This definition of the Arctic can be further divided into four different regions:

Moving inland from the coast over mainland North America and Eurasia, the moderating influence of the Arctic Ocean quickly diminishes, and the climate transitions from Arctic to subarctic, generally in less than 500 kilometres (300 mi), and often over a much shorter distance.

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