University of Alaska Fairbanks    |    Scenarios Network for Alaska + Arctic Planning


Mean annual precipitation (total rainwater equivalent) varies from over 7500 mm (300 in) in parts of southeastern Alaska to 100 mm (4 in) along the Arctic coast. These layers show cumulative annual precipitation across Alaska.

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  • ✓  Historical (1980–2009)
  • Projected Mid–Century (2040–2069, NCAR CCSM4, RCP 8.5)


These layers show historical or projected cumulative annual precipitation across Alaska. Solid precipitation (ice and snow) are measured as water equivalent here.

≥ 400in

The Pacific Mountain System intercepts much of the moisture in the air leaving the North Pacific Ocean. To the north, additional mountain ranges dry the air, further decreasing mean annual precipitation to as little as four inches per year north of the Brooks Range. The Bering Sea and Arctic Ocean are relatively poor sources of moisture for precipitation.

The Arctic and Interior (area between the Brooks Range to the north and the Alaska Range to the south) regions are often classed as semiarid and arid because of their low rainfall. However, due to permafrost, which prevents subterranean drainage, and low evaporation and transpiration rates (particularly during the winters) water needs are less than at lower latitudes.

The Interior is generally not a water–limited ecosystem, with large areas of wet muskeg and lakes as well as significant river runoff. In the Arctic, countless shallow lakes disguise the fact that water supplies are limited, though the area never exhibits the standard desert environmental characteristics.

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