1. WeatherSpark.com
  2. United States
  3. Alaska
  4. Anchorage

Average Weather in Anchorage Alaska, United States

In Anchorage, the summers are cool and mostly cloudy and the winters are long, freezing, snowy, and partly cloudy. Over the course of the year, the temperature typically varies from 13°F to 68°F and is rarely below -8°F or above 75°F.

Climate Summary

freezingvery coldcoldcoolcomfortablecoolcoldfreezingJanFebMarAprMayJunJulAugSepOctNovDec48%48%37%37%overcastclearprecipitation: 3.1 inprecipitation: 3.1 in0.6 in0.6 inmuggy: 0%muggy: 0%0%0%drydrytourism score: 4.5tourism score: 4.50.00.0
Click on each chart for more information.

Based on the tourism score, the best time of year to visit Anchorage for warm-weather activities is from late June to early August.

Temperature

The warm season lasts for 3.7 months, from May 19 to September 11, with an average daily high temperature above 59°F. The hottest day of the year is July 20, with an average high of 68°F and low of 55°F.

The cold season lasts for 4.0 months, from November 6 to March 5, with an average daily high temperature below 32°F. The coldest day of the year is January 17, with an average low of 13°F and high of 23°F.

Average High and Low Temperature

The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Average Hourly Temperature

Average Hourly Temperature in AnchorageJanFebMarAprMayJunJulAugSepOctNovDec12 AM4 AM8 AM12 PM4 PM8 PM12 AMcoolcoldfreezingvery coldcomfortable
The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < very cold < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The shaded overlays indicate night and civil twilight.

Clouds

In Anchorage, the average percentage of the sky covered by clouds experiences mild seasonal variation over the course of the year.

The clearer part of the year in Anchorage begins around February 14 and lasts for 2.2 months, ending around April 21. On March 16, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 48% of the time, and overcast or mostly cloudy 52% of the time.

The cloudier part of the year begins around April 21 and lasts for 9.8 months, ending around February 14. On December 18, the cloudiest day of the year, the sky is overcast or mostly cloudy 63% of the time, and clear, mostly clear, or partly cloudy 37% of the time.

Cloud Cover Categories

Cloud Cover Categories in AnchorageclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Mar 1648%Mar 1648%Dec 1837%Dec 1837%Feb 1442%Feb 1442%Apr 2143%Apr 2143%partly cloudyclearovercastmostly clearmostly cloudy
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.

Precipitation

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Anchorage varies throughout the year.

The wetter season lasts 3.6 months, from July 10 to October 29, with a greater than 26% chance of a given day being a wet day. The chance of a wet day peaks at 39% on September 27.

The drier season lasts 8.4 months, from October 29 to July 10. The smallest chance of a wet day is 13% on March 28.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation in Anchorage changes throughout the year.

Rain alone is the most common for 7.6 months, from March 20 to November 6. The highest chance of a day with rain alone is 38% on September 23.

Snow alone is the most common for 4.4 months, from November 6 to March 20. The highest chance of a day with snow alone is 17% on December 15.

Daily Chance of Precipitation

Daily Chance of Precipitation in AnchoragesnowrainsnowJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Sep 2739%Sep 2739%Mar 2813%Mar 2813%Nov 624%Nov 624%Jan 124%Jan 124%Jul 1026%Jul 1026%rainsnowmixed
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Anchorage experiences significant seasonal variation in monthly rainfall.

The rainy period of the year lasts for 7.5 months, from April 12 to November 29, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around September 5, with an average total accumulation of 3.1 inches.

The rainless period of the year lasts for 4.5 months, from November 29 to April 12. The least rain falls around March 14, with an average total accumulation of 0.3 inches.

Average Monthly Rainfall

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.

Snowfall

We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. Colder, drier snow tends to be on the higher end of that range and warmer, wetter snow on the lower end.

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Anchorage experiences some seasonal variation in monthly liquid-equivalent snowfall.

The snowy period of the year lasts for 6.4 months, from October 2 to April 14, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around December 12, with an average total liquid-equivalent accumulation of 1.0 inches.

The snowless period of the year lasts for 5.6 months, from April 14 to October 2. The least snow falls around July 18, with an average total liquid-equivalent accumulation of 0.0 inches.

Average Liquid-Equivalent Monthly Snowfall

Average Liquid-Equivalent Monthly Snowfall in AnchoragesnowsnowJanFebMarAprMayJunJulAugSepOctNovDec0.0 in0.5 in1.0 in1.5 in2.0 in2.5 in3.0 inDec 121.0 inDec 121.0 inJul 180.0 inJul 180.0 inOct 20.1 inOct 20.1 inApr 140.1 inApr 140.1 in
The average liquid-equivalent snowfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average rainfall.

Sun

The length of the day in Anchorage varies extremely over the course of the year. In 2017, the shortest day is December 21, with 5 hours, 27 minutes of daylight; the longest day is June 20, with 19 hours, 22 minutes of daylight.

Hours of Daylight and Twilight

The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise is at 4:19 AM on June 19, and the latest sunrise is 5 hours, 56 minutes later at 10:15 AM on December 26. The earliest sunset is at 3:40 PM on December 16, and the latest sunset is 8 hours, 3 minutes later at 11:42 PM on June 22.

Daylight saving time (DST) is observed in Anchorage during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.

Sunrise & Sunset with Twilight and Daylight Saving Time

Sunrise & Sunset with Twilight and Daylight Saving Time in AnchorageJanFebMarAprMayJunJulAugSepOctNovDec2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AM2 AMJun 194:19 AMJun 194:19 AM11:42 PMJun 2211:42 PMJun 22Dec 163:40 PMDec 163:40 PM10:15 AMDec 2610:15 AMDec 26Mar 12DSTMar 12DSTDSTNov 5DSTNov 5daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day over the course of the year 2017. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray. The transitions to and from daylight saving time are indicated by the 'DST' labels.

Humidity

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

The perceived humidity level in Anchorage, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, remaining a virtually constant 0% throughout.

Humidity Comfort Levels

Humidity Comfort Levels in AnchorageJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Jan 20%Jan 20%Jul 40%Jul 40%drydry
The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.

Wind

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Anchorage experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 7.1 months, from September 14 to April 17, with average wind speeds of more than 5.4 miles per hour. The windiest day of the year is January 8, with an average hourly wind speed of 6.6 miles per hour.

The calmer time of year lasts for 4.9 months, from April 17 to September 14. The calmest day of the year is July 6, with an average hourly wind speed of 4.2 miles per hour.

Average Wind Speed

Average Wind Speed in AnchoragewindywindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph1 mph2 mph3 mph4 mph5 mph6 mph7 mph8 mph9 mph10 mph11 mphJan 86.6 mphJan 86.6 mphJul 64.2 mphJul 64.2 mphSep 145.4 mphSep 145.4 mphApr 175.4 mphApr 175.4 mph
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The predominant average hourly wind direction in Anchorage varies throughout the year.

The wind is most often from the south for 4.1 months, from May 8 to September 11, with a peak percentage of 59% on July 3. The wind is most often from the east for 3.7 weeks, from September 11 to October 7 and for 5.3 months, from November 30 to May 8, with a peak percentage of 38% on September 23. The wind is most often from the north for 1.8 months, from October 7 to November 30, with a peak percentage of 50% on November 6.

Wind Direction

Wind Direction in AnchorageESENEJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%eastnorthsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Water Temperature

Anchorage is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average water temperature experiences significant seasonal variation over the course of the year.

The time of year with warmer water lasts for 2.8 months, from July 1 to September 24, with an average temperature above 50°F. The day of the year with the warmest water is August 14, with an average temperature of 55°F.

The time of year with cooler water lasts for 5.8 months, from November 25 to May 18, with an average temperature below 37°F. The day of the year with the coolest water is March 2, with an average temperature of 32°F.

Average Water Temperature

The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.

Best Time of Year to Visit

To characterize how pleasant the weather is in Anchorage throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Anchorage for general outdoor tourist activities is from late June to early August, with a peak score in the third week of July.

Tourism Score

Tourism Score in AnchorageJanFebMarAprMayJunJulAugSepOctNovDec02468104.54.50.00.0 precipitationprecipitationcloudscloudstemperaturetemperaturetourism score
The tourism score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Anchorage for hot-weather activities is from late June to late July, with a peak score in the second week of July.

Beach/Pool Score

Beach/Pool Score in AnchorageJanFebMarAprMayJunJulAugSepOctNovDec02468100.20.20.00.0 precipitationprecipitationcloudscloudstemperaturetemperature
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Growing Season

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in Anchorage typically lasts for 5.1 months (156 days), from around April 25 to around September 29, rarely starting before April 10 or after May 12, and rarely ending before September 11 or after October 15.

Time Spent in Various Temperature Bands and the Growing Season

Time Spent in Various Temperature Bands and the Growing Season in Anchoragegrowing seasonJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Apr 2550%Apr 2550%Sep 2950%Sep 2950%May 1290%May 1290%Sep 1190%Sep 1190%Apr 1010%Apr 1010%Oct 1510%Oct 1510%0%Nov 300%Nov 30Jul 12100%Jul 12100%very coldcoldcoolfrigidfreezing
The percentage of time spent in various temperature bands: frigid < 15°F < freezing < 32°F < very cold < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The black line is the percentage chance that a given day is within the growing season.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

Based on growing degree days alone, the first spring blooms in Anchorage should appear around May 31, only rarely appearing before May 21 or after June 12.

Growing Degree Days

Growing Degree Days in AnchorageJanFebMarAprMayJunJulAugSepOctNovDec0°F200°F400°F600°F800°F1,000°F1,200°FMay 3190°FMay 3190°FSep 3900°FSep 3900°FDec 31976°FDec 31976°F
The average growing degree days accumulated over the course of the year, with 25th to 75th and 10th to 90th percentile bands.

Solar Energy

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences extreme seasonal variation over the course of the year.

The brighter period of the year lasts for 3.0 months, from May 1 to July 31, with an average daily incident shortwave energy per square meter above 4.7 kWh. The brightest day of the year is June 10, with an average of 5.8 kWh.

The darker period of the year lasts for 4.1 months, from October 18 to February 21, with an average daily incident shortwave energy per square meter below 1.3 kWh. The darkest day of the year is December 21, with an average of 0.1 kWh.

Average Daily Incident Shortwave Solar Energy

The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

Topography

For the purposes of this report, the geographical coordinates of Anchorage are 61.218 deg latitude, -149.900 deg longitude, and 69 ft elevation.

The topography within 2 miles of Anchorage contains only modest variations in elevation, with a maximum elevation change of 177 feet and an average elevation above sea level of 48 feet. Within 10 miles contains only modest variations in elevation (3,212 feet). Within 50 miles contains large variations in elevation (7,936 feet).

The area within 2 miles of Anchorage is covered by artificial surfaces (79%) and sparse vegetation (14%), within 10 miles by water (29%) and trees (22%), and within 50 miles by trees (32%) and shrubs (21%).

Data Sources

This report illustrates the typical weather in Anchorage, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.

Temperature and Dew Point

There are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Anchorage.

For each station, the records are corrected for the elevation difference between that station and Anchorage according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.

The estimated value at Anchorage is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Anchorage and a given station.

The stations contributing to this reconstruction are: Merrill Field Airport (70%, 2.4 kilometers, east) and Lake Hood Seaplane Base (30%, 5.7 kilometers, southwest).

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.

All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.

Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.

Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.

Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .

Time zones for aiports and weather stations are provided by AskGeo.com .

Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.

Disclaimer

The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.

We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.

We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.