Climate of Anchorage

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First winter snowfall on the Chugach Mountains in September 2005

Anchorage, Alaska has a subarctic climate with the code Dfc 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 75.59 inches, or 1.92 meters.[1] Further afield at the 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 in (56 cm) 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)
J
F
M
A
M
J
J
A
S
O
N
D
 
 
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, making it the snowiest winter on record, while the least snowy winter on record was 2014–2015 (25.1 inches or 0.64 metres).[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 mi (126 km) west of the city.[9] The eruption deposited about 3 mm (0.12 in) 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 90 °F or 32.2 °C on July 4, 2019.[10] The average annual precipitation at the airport is 16.63 inches or 422.4 millimetres.[1]

Because of Anchorage’s high 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]

Classifications[]

Anchorage Climate according to major climate systems
Climatic scheme Initials Description
Köppen system[12] Dfc Continental subarctic climate[a]
Trewartha system[13][14] E Boreal climate
Alisov system[15] N/A Temperate climate[b]
Strahler system[16] N/A Boreal forest climate
Thornthwaite system[17]
B1 C'1
 Humid and microthermal
Neef system[18][19] N/A West side/maritime climate

Data[]

NWS Office/International Airport[]

hideClimate data for Ted Stevens Anchorage International Airport (1991−2020 normals,[20] extremes 1953−present)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Record high °F (°C) 50
(10) 		49
(9) 		53
(12) 		69
(21) 		77
(25) 		85
(29) 		90
(32) 		82
(28) 		73
(23) 		64
(18) 		54
(12) 		51
(11) 		90
(32)
Mean maximum °F (°C) 42
(6) 		43
(6) 		44
(7) 		56
(13) 		70
(21) 		74
(23) 		76
(24) 		74
(23) 		65
(18) 		55
(13) 		43
(6) 		42
(6) 		78
(26)
Average high °F (°C) 22.7
(−5.2) 		27.3
(−2.6) 		33.0
(0.6) 		45.1
(7.3) 		56.3
(13.5) 		63.4
(17.4) 		66.2
(19.0) 		64.0
(17.8) 		55.7
(13.2) 		42.0
(5.6) 		28.9
(−1.7) 		25.0
(−3.9) 		44.1
(6.7)
Daily mean °F (°C) 16.9
(−8.4) 		21.3
(−5.9) 		25.8
(−3.4) 		37.5
(3.1) 		48.1
(8.9) 		55.9
(13.3) 		59.6
(15.3) 		57.5
(14.2) 		49.3
(9.6) 		36.3
(2.4) 		23.6
(−4.7) 		19.4
(−7.0) 		37.6
(3.1)
Average low °F (°C) 11.0
(−11.7) 		15.2
(−9.3) 		18.6
(−7.4) 		29.9
(−1.2) 		40.0
(4.4) 		48.4
(9.1) 		52.9
(11.6) 		50.9
(10.5) 		42.9
(6.1) 		30.7
(−0.7) 		18.3
(−7.6) 		13.8
(−10.1) 		31.0
(−0.6)
Mean minimum °F (°C) −9
(−23) 		−4
(−20) 		1
(−17) 		18
(−8) 		31
(−1) 		40
(4) 		47
(8) 		43
(6) 		31
(−1) 		16
(−9) 		1
(−17) 		−5
(−21) 		−13
(−25)
Record low °F (°C) −34
(−37) 		−28
(−33) 		−24
(−31) 		−4
(−20) 		17
(−8) 		33
(1) 		36
(2) 		31
(−1) 		19
(−7) 		−5
(−21) 		−21
(−29) 		−30
(−34) 		−34
(−37)
Average precipitation inches (mm) 0.75
(19) 		0.86
(22) 		0.69
(18) 		0.43
(11) 		0.65
(17) 		1.02
(26) 		1.82
(46) 		2.93
(74) 		3.10
(79) 		1.82
(46) 		1.19
(30) 		1.16
(29) 		16.42
(417)
Average snowfall inches (cm) 12.4
(31) 		13.4
(34) 		11.0
(28) 		4.0
(10) 		0.3
(0.76) 		0.0
(0.0) 		0.0
(0.0) 		0.0
(0.0) 		0.4
(1.0) 		5.6
(14) 		12.6
(32) 		18.2
(46) 		77.9
(198)
Average precipitation days (≥ 0.01 in) 8.1 7.9 6.0 4.9 6.5 8.6 11.7 14.4 14.9 11.5 9.8 10.8 115.1
Average snowy days (≥ 0.1 in) 8.8 7.8 6.1 2.5 0.3 0.0 0.0 0.0 0.3 3.2 7.7 10.8 47.5
Average relative humidity (%) 73.4 71.4 66.1 64.3 61.6 65.6 71.4 75.1 75.9 74.5 77.1 77.1 71.1
Average dew point °F (°C) 8.1
(−13.3) 		11.1
(−11.6) 		15.4
(−9.2) 		24.1
(−4.4) 		33.4
(0.8) 		42.4
(5.8) 		48.6
(9.2) 		47.8
(8.8) 		40.6
(4.8) 		27.0
(−2.8) 		15.3
(−9.3) 		10.6
(−11.9) 		27.0
(−2.8)
Mean monthly sunshine hours 82.9 120.5 195.8 235.3 288.7 274.7 250.1 203.9 159.8 117.1 80.6 51.8 2,061.2
Percent possible sunshine 41 48 53 53 53 48 44 42 41 38 37 30 46
Average ultraviolet index 0 0 1 2 4 5 5 4 2 1 0 0 2
Source 1: NOAA (relative humidity and sun 1961–1990)[21][22][23]
Source 2: Weather Atlas (UV)[24]
Climate data for Anchorage
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Average sea temperature °F (°C) 36.9
(2.8) 		35.8
(2.1) 		36.1
(2.3) 		37.5
(3.0) 		42.4
(5.8) 		47.7
(8.8) 		52.4
(11.3) 		53.1
(11.7) 		51.6
(10.9) 		47.5
(8.6) 		43.0
(6.1) 		39.6
(4.2) 		43.6
(6.5)
Mean daily daylight hours 7.0 9.0 12.0 15.0 18.0 19.0 18.0 16.0 13.0 10.0 7.0 6.0 12.5
Source: Weather Atlas[24]

See or edit raw graph data.

Campbell Airstrip[]

Climate data for Campbell Airstrip (Anchorage Alaska)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Average high °F (°C) 20
(−7) 		26
(−3) 		35
(2) 		45
(7) 		58
(14) 		66
(19) 		68
(20) 		65
(18) 		55
(13) 		41
(5) 		26
(−3) 		22
(−6) 		44
(7)
Average low °F (°C) 2
(−17) 		4
(−16) 		9
(−13) 		22
(−6) 		33
(1) 		41
(5) 		47
(8) 		44
(7) 		35
(2) 		22
(−6) 		7
(−14) 		5
(−15) 		23
(−5)
Average snowfall inches (cm) 10
(25) 		16
(41) 		18
(46) 		9
(23) 		0.2
(0.51) 		0
(0) 		0
(0) 		0
(0) 		0
(0) 		9
(23) 		11
(28) 		2
(5.1) 		75.2
(191.61)
Source: NOAA[25]

Notes[]

  1. ^ Or only subarctic climate
  2. ^ Mid-latitude temperate interior climate

References[]

  1. ^ Jump up to: a b "NowData - NOAA Online Weather Data". National Oceanic and Atmospheric Administration. Retrieved 2011-05-22.
  2. ^ https://w2.weather.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. Archived from the original on 2011-07-28. Retrieved 2011-05-22.
  6. ^ "PAFC March 2002 Precipitation". National Weather Service. March 2002. Archived from the original on 2011-07-28. Retrieved 2011-05-22.
  7. ^ Jump up to: a b c "Snowfall Records for Anchorage Alaska" (PDF). National Oceanic and Atmospheric Administration. Archived from the original (PDF) on 2013-02-20. Retrieved 2012-04-01.
  8. ^ "Temperature Records for Anchorage Alaska" (PDF). National Oceanic and Atmospheric Administration. Archived from the original (PDF) on 2013-02-20. 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. ^ Service, NOAA's National Weather. "NWSChat - NOAA's National Weather Service". nwschat.weather.gov. Retrieved 2019-08-06.
  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.CS1 maint: archived copy as title (link) for an explanation of the concept “percent possible sunlight.” Data from Data Through 2005 Average Percent Possible Sunshine Archived 2008-06-17 at the Wayback Machine. National Climatic Data Center. Last accessed November 20, 2006.
  12. ^ "Anchorage - University of Alaska, Alaska Köppen Climate Classification (Weatherbase)". Weatherbase. Retrieved 2019-07-03.
  13. ^ "GLOBAL ECOLOGICAL ZONING FOR THE GLOBAL FOREST RESOURCES ASSESSMENT 2000". www.fao.org. Retrieved 2019-07-01.
  14. ^ "Trewartha maps". kkh.ltrr.arizona.edu. Retrieved 2019-07-03.
  15. ^ Cmapm, Kliimavöötmed svg: Urmasderivative work (2011-06-16), Русский: Климатические пояса Земли по Б. П. Алисову., retrieved 2019-07-01
  16. ^ "World Strahler Climate Map".
  17. ^ Feddema, Johannes J. (January 2005). "A Revised Thornthwaite-Type Global Climate Classification". Physical Geography. 26 (6): 442–466. doi:10.2747/0272-3646.26.6.442. ISSN 0272-3646.
  18. ^ "Klimaklassifikation". www.spektrum.de (in German). Retrieved 2019-07-01.
  19. ^ "Klimazonen nach E. Neef (1989)". Klett-Perthes.
  20. ^ 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 1991 to 2020.
  21. ^ "NowData - NOAA Online Weather Data". National Oceanic and Atmospheric Administration. Retrieved May 29, 2021.
  22. ^ "Station: Anchorage INTL AP, AK". U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991-2020). National Oceanic and Atmospheric Administration. Retrieved May 29, 2021.
  23. ^ "WMO climate normals for Anchorage/INTL, AK 1961−1990". National Oceanic and Atmospheric Administration. Retrieved August 30, 2020.
  24. ^ Jump up to: a b "Anchorage, Alaska, USA - Monthly weather forecast and Climate data". Weather Atlas. Retrieved July 4, 2019.
  25. ^ "NOAA Weather Data, 1981–2010".
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