Climate of Anchorage

First winter snowfall on the Chugach Mountains in September 2005

Anchorage, Alaska has a subarctic climate with the code Dsc according to the Köppen climate classification due to its short, cool summers. Average daytime summer temperatures range from approximately 55 to 78 °F (12.8 to 25.6 °C); average daytime winter temperatures are about 5 to 30 °F (−15.0 to −1.1 °C). Anchorage has a frost-free growing season that averages slightly over one hundred days.

Average January low and high temperatures at Ted Stevens Anchorage International Airport (PANC) are 11 / 23 °F (−11.7 / −5.0 °C) with an average winter snowfall of 75.5 inches or 1.92 metres.[1] Further afield at the Campbell Airstrip is another weather station recording colder night temperatures in both summer and winter. [2]

The weather on any given day and indeed for entire seasons can be very unpredictable. Some winters feature several feet of snow and cold temperatures, while others like that of 1976–77[3] (in the January of which Anchorage amazingly averaged 2.7 °F or 1.5 °C warmer than Atlanta almost 30 degrees closer to the equator),[4] just a foot or two of snow and frequent thaws, which put dangerous ice on the streets.

On March 17, 2002, there was a storm causing 22 inches of snow[5] closing schools for the next two days. The storm broke the city record for the most snowfall in a single day. The storm, which started the evening of March 16, easily surpassed the old record of 15.6 inches or 0.40 metres recorded on 28 December and 29 December 1955. On March 17, 22 inches or 0.56 metres were measured by the National Weather Service,[6][7] topping the old record of 15.6 inches or 0.40 metres set on December 29, 1955.[7]

Anchorage
Climate chart (explanation)
JFMAMJJASOND
 
 
0.7
 
 
23
11
 
 
0.7
 
 
27
14
 
 
0.6
 
 
34
19
 
 
0.5
 
 
45
29
 
 
0.8
 
 
56
39
 
 
1
 
 
63
47
 
 
1.8
 
 
66
52
 
 
3.2
 
 
64
49
 
 
3
 
 
55
41
 
 
2
 
 
40
29
 
 
1.2
 
 
27
17
 
 
1.1
 
 
24
13
Average max. and min. temperatures in °F
Precipitation totals in inches

The 2011-2012 winter had 134.5 inches or 3.42 metres, which made it the snowiest winter on record while the least snowiest winter of record was 2014-2015 when 25.1 inches or 0.64 metres of snow fell.[7] The coldest temperature ever recorded at the original weather station located at Merrill Field on the East end of 5th Avenue was −38 °F or −38.9 °C on February 3, 1947.[8]

Due to its proximity to active volcanoes, ash hazards are a significant, though infrequent, occurrence. The most recent notable incident was an August, 1992 eruption of Mt. Spurr, which is located 78 miles west of the city.[9] The eruption deposited about 3 mm of volcanic ash on the city. The clean-up of ash resulted in excessive demands for water and caused major problems for the Anchorage Water and Wastewater Utility.

Summers are typically mild (although cool compared to the contiguous US and even interior Alaska), though it can rain frequently. Average July low and high temperatures are 52 / 66 °F (11.1 / 18.9 °C) and the hottest reading ever recorded was 87 °F or 30.6 °C on June 18, 2013.[10] The average annual precipitation at the airport is 16.63 inches or 422.4 millimetres.[1]

Because of Anchorage’s latitude, summer days are very long and winter daylight hours are very short. Anchorage is often cloudy during the winter, which decreases the amount of sunlight experienced by residents.[11]

References

  1. 1 2 3 "NowData - NOAA Online Weather Data". National Oceanic and Atmospheric Administration. Retrieved 2017-08-28.
  2. ↑ http://www.nws.noaa.gov/climate/xmacis.php?wfo=pafg
  3. ↑ Namias, Joseph; ‘Multiple Causes of the North American Abnormal Winter, 1976-77’; in Monthly Weather Review 106: 279-295
  4. ↑ Wagner, A. James (1977). "Weather and Circulation of January 1977 — The Coldest Month on Record in the Ohio Valley". Monthly Weather Review. 105: 553–560. Bibcode:1977MWRv..105..553W. doi:10.1175/1520-0493(1977)105<0553:WACOJ>2.0.CO;2.
  5. ↑ "PAFC March 2002 Precipitation". National Weather Service. March 2002. Retrieved 2011-05-22.
  6. ↑ "PAFC March 2002 Precipitation". National Weather Service. March 2002. Retrieved 2011-05-22.
  7. 1 2 3 "Snowfall Records for Anchorage Alaska" (PDF). National Oceanic and Atmospheric Administration. Retrieved 2012-04-01.
  8. ↑ "Temperature Records for Anchorage Alaska" (PDF). National Oceanic and Atmospheric Administration. Retrieved 2012-04-01.
  9. ↑ "Mt. Spurr's 1992 Eruptions". Alaska Volcano Observatory. Archived from the original on 2008-12-09. Retrieved 2008-11-26.
  10. ↑ Alaska Bakes with Alltime Heat Records
    Weather Underground. June 21, 2013. Retrieved January 20, 2016
  11. ↑ For November, December, and January, average monthly percent possible sunshine (the hours of direct sunlight experienced, divided by the possible hours of sunlight for the location) is below 35%. See "Archived copy". Archived from the original on 2012-10-19. Retrieved 2012-10-15. for an explanation of the concept “percent possible sunlight.” Data from Data Through 2005 Average Percent Possible Sunshine. National Climatic Data Center. Last accessed November 20, 2006.
  12. ↑ The office is located at 61°09′22″N 149°59′02″W / 61.1562°N 149.9840°W, just south of the airport grounds. Anchorage weather data were recorded at Merrill Field from February 1916 to January 1953 and at Ted Stevens Anchorage International Airport from February 1953 to January 1998; the data have been recorded at the NWS office since February 1998.
  13. ↑ Mean monthly maxima and minima (i.e. the highest and lowest temperature readings during an entire month or year) calculated based on data at said location from 1981 to 2010.
  14. ↑ "Station Name: AK ANCHORAGE FRCST OFC". National Oceanic and Atmospheric Administration. Retrieved 2014-03-13.
  15. ↑ "Monthly Averages for Anchorage, AK". The Weather Channel. Retrieved 2009-10-07.
  16. ↑ "Station Name: AK ANCHORAGE INTL AP". National Oceanic and Atmospheric Administration. Retrieved 2014-03-11.
  17. ↑ "WMO climate normals for Anchorage/INTL, AK 1961−1990". National Oceanic and Atmospheric Administration. Retrieved 17 February 2015.
  18. ↑ "NOAA Weather Data, 1981–2010".
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