1. WeatherSpark.com
  2. United States
  3. Alaska
  4. Unalaska Airport

Average Weather at Unalaska Airport Alaska, United States

At Unalaska Airport, the summers are short, cool, and windy; the winters are long, very cold, wet, and extremely windy; and it is overcast year round. Over the course of the year, the temperature typically varies from 31°F to 57°F and is rarely below 22°F or above 63°F.

Climate Summary

very coldcoldcoolcoldvery coldJanFebMarAprMayJunJulAugSepOctNovDec41%41%18%18%overcastclearprecipitation: 4.3 inprecipitation: 4.3 in1.8 in1.8 inmuggy: 0%muggy: 0%0%0%drydrytourism score: 1.5tourism score: 1.50.00.0
Click on each chart for more information.

Based on the tourism score, the best time of year to visit Unalaska Airport for warm-weather activities is for the entire month of August.

Temperature

The warm season lasts for 2.6 months, from June 30 to September 16, with an average daily high temperature above 53°F. The hottest day of the year is August 14, with an average high of 57°F and low of 49°F.

The cold season lasts for 4.8 months, from November 26 to April 19, with an average daily high temperature below 40°F. The coldest day of the year is January 23, with an average low of 31°F and high of 36°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 at Unalaska AirportJanFebMarAprMayJunJulAugSepOctNovDec12 AM4 AM8 AM12 PM4 PM8 PM12 AMvery coldvery coldcold
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.

Evjen, Norway (4,000 miles away) is the far-away foreign place with temperatures most similar to Unalaska Airport (view comparison).

Clouds

At Unalaska Airport, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.

The clearer part of the year at Unalaska Airport begins around September 1 and lasts for 2.9 months, ending around November 29. On October 14, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 41% of the time, and overcast or mostly cloudy 59% of the time.

The cloudier part of the year begins around November 29 and lasts for 9.1 months, ending around September 1. On July 17, the cloudiest day of the year, the sky is overcast or mostly cloudy 82% of the time, and clear, mostly clear, or partly cloudy 18% of the time.

Cloud Cover Categories

Cloud Cover Categories at Unalaska AirportclearercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Oct 1441%Oct 1441%Jul 1718%Jul 1718%Sep 129%Sep 129%Nov 2930%Nov 2930%clearmostly clearpartly cloudymostly cloudyovercast
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 at Unalaska Airport varies throughout the year.

The wetter season lasts 6.6 months, from September 1 to March 20, with a greater than 36% chance of a given day being a wet day. The chance of a wet day peaks at 48% on December 17.

The drier season lasts 5.4 months, from March 20 to September 1. The smallest chance of a wet day is 25% on May 5.

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 throughout the year is rain alone, with a peak probability of 43% on November 10.

Daily Chance of Precipitation

Daily Chance of Precipitation at Unalaska AirportwetwetdryJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Dec 1748%Dec 1748%May 525%May 525%Sep 136%Sep 136%Mar 2036%Mar 2036%rainsnow
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. Unalaska Airport experiences significant seasonal variation in monthly rainfall.

Rain falls throughout the year at Unalaska Airport. The most rain falls during the 31 days centered around December 9, with an average total accumulation of 4.0 inches.

The least rain falls around April 25, with an average total accumulation of 1.7 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. Unalaska Airport experiences some seasonal variation in monthly liquid-equivalent snowfall.

The snowy period of the year lasts for 4.4 months, from November 24 to April 7, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around January 27, with an average total liquid-equivalent accumulation of 0.6 inches.

The snowless period of the year lasts for 7.6 months, from April 7 to November 24. The least snow falls around August 5, with an average total liquid-equivalent accumulation of 0.0 inches.

Average Liquid-Equivalent Monthly Snowfall

Average Liquid-Equivalent Monthly Snowfall at Unalaska AirportsnowsnowJanFebMarAprMayJunJulAugSepOctNovDec0 in1 in2 in3 in4 inJan 270.6 inJan 270.6 inAug 50.0 inAug 50.0 inNov 240.1 inNov 240.1 inApr 70.1 inApr 70.1 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 at Unalaska Airport varies extremely over the course of the year. In 2017, the shortest day is December 21, with 7 hours, 23 minutes of daylight; the longest day is June 20, with 17 hours, 7 minutes of daylight.

Hours of Daylight and Twilight

Hours of Daylight and Twilight at Unalaska AirportJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 9 minMar 2012 hr, 9 minMar 2017 hr, 7 minJun 2017 hr, 7 minJun 2012 hr, 11 minSep 2212 hr, 11 minSep 227 hr, 23 minDec 217 hr, 23 minDec 21nightnightday
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 6:33 AM on June 17, and the latest sunrise is 3 hours, 51 minutes later at 10:24 AM on December 29. The earliest sunset is at 5:44 PM on December 13, and the latest sunset is 5 hours, 58 minutes later at 11:42 PM on June 23.

Daylight saving time (DST) is observed at Unalaska Airport 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 at Unalaska AirportJanFebMarAprMayJunJulAugSepOctNovDec2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AM2 AMJun 176:33 AMJun 176:33 AM11:42 PMJun 2311:42 PMJun 23Dec 135:44 PMDec 135:44 PM10:24 AMDec 2910:24 AMDec 29Mar 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 at Unalaska Airport, 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 at Unalaska AirportJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Jan 230%Jan 230%Jul 250%Jul 250%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 at Unalaska Airport experiences extreme seasonal variation over the course of the year.

The windier part of the year lasts for 7.6 months, from September 13 to May 2, with average wind speeds of more than 15.6 miles per hour. The windiest day of the year is November 25, with an average hourly wind speed of 20.1 miles per hour.

The calmer time of year lasts for 4.4 months, from May 2 to September 13. The calmest day of the year is July 18, with an average hourly wind speed of 11.2 miles per hour.

Average Wind Speed

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 at Unalaska Airport varies throughout the year.

The wind is most often from the east for 6.0 days, from February 16 to February 22, with a peak percentage of 27% on February 16. The wind is most often from the north for 3.4 months, from February 22 to June 5 and for 1.8 months, from December 22 to February 16, with a peak percentage of 34% on April 20. The wind is most often from the west for 6.5 months, from June 5 to December 22, with a peak percentage of 44% on August 29.

Wind Direction

Wind Direction at Unalaska AirportNNWNJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%westsoutheastnorth
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

Unalaska Airport 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 some seasonal variation over the course of the year.

The time of year with warmer water lasts for 2.4 months, from July 15 to September 28, with an average temperature above 47°F. The day of the year with the warmest water is August 21, with an average temperature of 49°F.

The time of year with cooler water lasts for 4.6 months, from December 28 to May 16, with an average temperature below 41°F. The day of the year with the coolest water is March 16, with an average temperature of 39°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 at Unalaska Airport 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 Unalaska Airport for general outdoor tourist activities is for the entire month of August, with a peak score in the third week of August.

Tourism Score

Tourism Score at Unalaska AirportJanFebMarAprMayJunJulAugSepOctNovDec02468101.51.50.00.0 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 Unalaska Airport for hot-weather activities is from August 10 to August 19.

Beach/Pool Score

Beach/Pool Score at Unalaska AirportJanFebMarAprMayJunJulAugSepOctNovDec02468100.00.00.00.0precipitationprecipitationcloudscloudstemperaturetemperature
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 at Unalaska Airport typically lasts for 6.7 months (205 days), from around April 24 to around November 16, rarely starting before April 3 or after May 12, and rarely ending before October 20 or after December 20.

Time Spent in Various Temperature Bands and the Growing Season

Time Spent in Various Temperature Bands and the Growing Season at Unalaska Airportgrowing seasonJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%50%Apr 2450%Apr 2450%Nov 1650%Nov 1690%May 1290%May 1290%Oct 2090%Oct 2010%Apr 310%Apr 310%Dec 2010%Dec 200%Feb 20%Feb 2Jul 23100%Jul 23100%freezingvery coldcoldcool
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 at Unalaska Airport should appear around August 10, only rarely appearing before July 30 or after September 16.

Growing Degree Days

Growing Degree Days at Unalaska AirportJanFebMarAprMayJunJulAugSepOctNovDec0°F50°F100°F150°F200°F250°FAug 1090°FAug 1090°FDec 31191°FDec 31191°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 significant seasonal variation over the course of the year.

The brighter period of the year lasts for 3.3 months, from April 25 to August 4, with an average daily incident shortwave energy per square meter above 3.9 kWh. The brightest day of the year is May 30, with an average of 4.8 kWh.

The darker period of the year lasts for 3.7 months, from October 27 to February 18, with an average daily incident shortwave energy per square meter below 1.3 kWh. The darkest day of the year is December 16, with an average of 0.4 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 Unalaska Airport are 53.900 deg latitude, -166.544 deg longitude, and 0 ft elevation.

The topography within 2 miles of Unalaska Airport contains very significant variations in elevation, with a maximum elevation change of 1,611 feet and an average elevation above sea level of 109 feet. Within 10 miles contains very significant variations in elevation (3,540 feet). Within 50 miles also contains extreme variations in elevation (5,971 feet).

The area within 2 miles of Unalaska Airport is covered by water (79%), within 10 miles by water (43%) and shrubs (24%), and within 50 miles by water (86%).

Data Sources

This report illustrates the typical weather at Unalaska Airport, 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

Unalaska Airport has a weather station that reported reliably enough during the analysis period that we have included it in our network. When available, historical temperature and dew point measurements are taken directly from this weather station. These records are obtained from NOAA's Integrated Surface Hourly data set, falling back on ICAO METAR records as required.

There are no other weather stations in our network within 200 kilometers of this location. Consequently, in the case of missing or erroneous measurements from this station, we fall back on NASA's MERRA-2 modern-era reanalysis , adjusted according to typical seasonal and diurnal differences between this station and the wide-area MERRA-2 reconstructed values.

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.