Barrow, Alaska - Geography - Climate

Climate

Owing to its location 320 miles (515 km) north of the Arctic Circle, Barrow's climate is cold and dry, and is classified as a polar climate (Köppen ET). Winter weather can be extremely dangerous because of the combination of cold and wind, while summers are cool even at their warmest. Weather observations are available for Barrow dating back to the late 19th century. Currently there is a National Weather Service (NWS) Office and a National Oceanic and Atmospheric Administration (NOAA) Climate Monitoring Lab in Barrow. The United States Department of Energy (DOE) also has a climate observation site in Barrow as part of its Atmospheric Radiation Measurement (ARM) Climate Research Facility.

Despite the extreme northern location, temperatures at Barrow are moderated by the surrounding topography. The Arctic Ocean is on three sides, and flat tundra stretches some 200 miles (300 km) to the south. Thus, there are no wind barriers, and there are no protected valleys where dense cold air can settle or form temperature inversions in the lower atmosphere in the way that commonly happens in the Interior between the Brooks Range and the Alaska Range.

Nonetheless, Barrow experiences the lowest average temperatures in Alaska. Although it is rare for Barrow to record the lowest temperatures statewide during cold waves, extremely low wind chill and "white out" conditions from blowing snow are very common.

Temperatures remain below freezing from early October through late May. The high temperature is above freezing on an average of only 120 days per year, and there are temperatures at or below 0 °F (−18 °C) on an average of 160 days per year. Freezing temperatures, and snowfall, can occur during any month of the year.

In terms of precipitation, Barrow has a desert climate, and averages less than 5 inches (127 mm) "rainfall equivalent" per year, given that one inch of rain possesses approximately equal water content to 12 inches (30 cm) of snow. According to 1971–2000 normals, this includes 29 inches (74 cm) of snow, compared to 101 inches (257 cm) for Kuujjuaq in Nunavik, Quebec or 84 inches (213 cm) and 77 inches (196 cm) for much warmer Juneau and Kodiak respectively. Even Sable Island, at around 44 degrees latitude and under the influence of the Gulf Stream, receives 44 inches (112 cm), or 52 percent more snowfall than Barrow.

The first snow (defined as snow that will not melt until next spring) generally falls during the first week of October, when temperatures cease to rise above freezing during the day. October is usually the month with the heaviest snowfall, with measurable amounts occurring on nearly half the days and an average total accumulation of 8.8 inches (22 cm). Snow can also fall in the summer, and as a result, winter is given a far stricter definition than in places further south, including Fairbanks. If the standard definition were used, then winter would be said to last from early September through late June, which, given the unique culture of Barrow and its adaptation to the cold, would be inaccurate in this case.

The sun sets on November 18 or 19, and it remains below the horizon for about 65 days. This creates a polar night that lasts until the sun rises again around January 22 or January 23. During the first half of the polar night, there is a decreasing amount of twilight each day, and on the winter solstice (around December 21 or December 22), civil twilight in Barrow lasts for a mere 3 hours.

In addition to its low temperatures and polar night, Barrow is one of the cloudiest places on Earth. Owing to the prevailing easterly winds off the Arctic Ocean, Barrow is completely overcast slightly more than 50% of the year. It is at least 70% overcast 62% of the time. Cloud types are mainly low stratus and fog; cumuli forms are rare. Peak cloudiness occurs in August and September when the ocean is ice-free. Dense fog occurs an average of 65 days per year, mostly in the summer months. Ice fog is very common during the winter months, especially when the temperature drops below −30 °F (−34 °C).

Serious cold weather usually begins in January, and February is generally the coldest month, averaging −14.2 °F (−25.7 °C). By March 1, the sun is up for 9 hours, and temperatures begin to warm, though winds are usually higher. April brings less extreme temperatures, with an average of 1.8 °F (−16.8 °C), and on April 1 the sun is up for more than 14 hours. In May, the temperatures are much warmer, averaging 21.2 °F (−6.0 °C). Beginning on around May 11 or 12 the sun remains above the horizon the entire day, there is an increasing amount of twilight each day, and on the summer solstice (around June 21 or June 22), civil twilight in Barrow lasts for more than 3 hours and the phenomenon known as the midnight sun is observed. The sun does not set for about 80 days, until around July 31 or August 1. In June, the average temperature rises above freezing, to 35.7 °F (2.1 °C), and average daily temperatures remain above freezing until mid- or late September.

July is the warmest month of the year, with an average high of 47 °F (8 °C) and an average low temperature of 35 °F (2 °C). Beginning in late July, the Arctic Ocean is relatively ice-free, and remains so until late October. The highest temperature recorded in Barrow was 79 °F (26 °C) on July 13, 1993, while the lowest is −56 °F (−49 °C) on February 3, 1924; the highest minimum is 53 °F (12 °C), while the lowest maximum is −47 °F (−44 °C). Barrow records an average 24 days per year where the high reaches at least 50 °F (10 °C), and even in July and August, the low falls to or below the freezing mark on 24 days.

Variation of wind speed during the year is limited, with the fall months being windiest. Extreme winds from 40 to 60 miles per hour (60 to 100 km/h) have been recorded for all months. Winds average 12 mph (20 km/h) and are typically from the east.