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The climate of Alaska is determined by average temperatures and precipitation received statewide over many years. The extratropical storm track runs along the Aleutian Island chain, across the Alaska Peninsula, and along the coastal area of the Gulf of Alaska which exposes these parts of the state to a large majority of the storms crossing the North Pacific. Onshore flow into the various mountain chains across the state leads to significant spatial variability in precipitation, with snowfall constituting a bulk of the annual precipitation each year. The climate in Juneau and the southeast panhandle is a mid-latitude oceanic climate (Köppen Cfb) in the southern sections and a sub Arctic oceanic climate (Köppen Cfc) in the northern parts. The climate in Southcentral Alaska is a subarctic climate (Köppen Dfc) due to its short, cool summers. The climate of the interior of Alaska is best described as extreme and is the best example of a true subarctic climate, as the highest and lowest recorded temperatures in Alaska have both occurred in the interior. The climate in the extreme north of Alaska is an Arctic climate (Köppen ET) with long, very cold winters and short, cool summers.
The climate in Juneau and the southeast panhandle is best described as "a cooler version of Seattle." It is a mid-latitude oceanic climate (Köppen climate classification Cfb) in the southern sections and a sub Arctic oceanic climate (Köppen Cfc) in the northern parts. On an annual basis, this is both the wettest and warmest part of Alaska with milder temperatures in the winter and high precipitation throughout the year. This is also the only region in Alaska in which the average daytime high temperature is above freezing during the winter months.
The climate in south central Alaska, with Anchorage as a typical city, is mild by Alaskan standards. This is due in large part to its proximity to the coast. While it does not get nearly as much rain as the southeast of Alaska, it does get more snow, although days tend to be clearer here. It is a subarctic climate (Köppen Dfc) due to its short, cool summers. There are frequent, strong southeast winds known as the Knik wind in the vicinity of Palmer, especially in the winter months.
The climate of Western Alaska is determined largely by the Bering Sea and the Gulf of Alaska. It is a subarctic oceanic climate in the southwest and a continental subarctic climate farther north. The temperature is somewhat moderate considering how far north the area is. This area has a tremendous amount of variety, especially when considering precipitation. The northern side of the Seward Peninsula is technically a desert with less than of precipitation annually, while some locations between Dillingham and Bethel average around 2540mm of precipitation.
The climate of the interior of Alaska is best described as extreme and is the best example of a true subarctic climate. Some of the hottest and coldest temperatures in Alaska occur around the area near Fairbanks. The summers can have temperatures reaching into the 90s °F (near 34 °C), while in the winter, the temperature can fall below −60 °F (−51.1 °C).
The climate in the extreme north of Alaska is what would be expected for an area north of the Arctic Circle. It is an Arctic climate (Köppen ET) with long, very cold winters and short, cool summers. Even in July, the average low temperature is barely above freezing in Barrow, at 34 °F (1.1 °C).
The highest and lowest recorded temperatures in Alaska are both in the Interior. The highest is 100 °F (37.8 °C) in Fort Yukon on June 27, 1915. The lowest Alaska temperature is −80 °F (−62.2 °C) in Prospect Creek on January 23, 1971, 1°F (0.55°C) above the lowest temperature recorded in continental North America (in Snag, Yukon, Canada). Alaska also holds the extreme US record low temperatures for every month except July and August.
|Climate data for Alaska|
|Record high °F (°C)||62|
|Record low °F (°C)||−80|
Juneau averages over 50 inches (1,270 mm) of precipitation a year, while other areas in southeast Alaska receive over 275 inches (6,990 mm). South central Alaska does not get nearly as much rain as the southeast of Alaska, though it does get more snow. On average, Anchorage receives 16 inches (406 mm) of precipitation a year, with around 75 inches (1,905 mm) of snow. The northern coast of the Gulf of Alaska receives up to 150 inches (3,800 mm) of precipitation annually. Across western sections of the state, the northern side of the Seward Peninsula is a desert with less than 10 inches (250 mm) of precipitation annually, while some locations between Dillingham and Bethel average around 100 inches (2,540 mm) of precipitation. Inland, often less than 10 inches (250 mm) falls a year, but what precipitation falls during the winter tends to stay throughout the season. La Niña events lead to drier than normal conditions, while El Niño events do not have a correlation towards dry or wet conditions. Precipitation increases by 10 to 40 percent when the Pacific decadal oscillation is positive.