Climate and monthly weather forecastUnalaska, AK
Climate and monthly weather forecast
The climate of Unalaska
Owing to its geographical position and climatic conditions, Unalaska, Alaska, USA falls primarily within the ET category of the Köppen climate classification, also known as the Tundra climate. With a backdrop of relatively low temperatures and significant precipitation throughout the year, the city displays a clear-cut manifestation of this polar climate type.Temperature fluctuations during the year highlight a distinctive pattern. The year starts on a cooler note with the average high temperature in January registering at 35.1°F (1.7°C) and gradually increasing to 37.4°F (3°C) by April. The warmest months are July and August, where the high temperatures hover around 53.2°F (11.8°C), before starting their descent towards the year-end. On the other hand, the average low temperatures tiptoe from a year-start low of 31.6°F (-0.2°C) to a peak of 49.6°F (9.8°C) in August, again portraying a similar annual trend.
Precipitation in Unalaska also showcases variability across the annual timeline. The city receives maximum rainfall in December at 4.21" (107mm), while February is the driest with only 3.03" (77mm). Simultaneously, snowfall patterns reveal that January experiences the most snow with 6.97" (177mm), tapering off through spring and summer to virtually nonexistent levels, then gradually resuming from October.
The best time to visit Unalaska
Considering the combination of temperature, daylight, UV index, cloud%, and precipitation, the best time to visit Unalaska would be from June to August. During this period, the temperature oscillates between 46.4°F (8°C) and 53.2°F (11.8°C), the longest daylight will be at 17 hours, the sunshine ranges from 5.8 hours to 4.9 hours, and the UV index reaches peak values of 3.The worst time to visit Unalaska
The least favorable time to visit Unalaska would be from November to January. The temperature stoops to sub-40°F (-40°C) levels, the shortest daylight being at 7.5 hours and the sunshine reaching its annual minimum of 2 hours. The snowfall also hits its peak in January.Spring weather in Unalaska
Spring in Unalaska stretches from March with an average high temperature of 34.7°F (1.5°C) to May's warmer 41.4°F (5.2°C). During this transition, daylight expands from 11.9 hours to 16 hours, resulting in increased sunlight duration ranging from 3.9 hours to 5.2 hours. The rainfall and snowfall decrease significantly, leading to relatively moist and chilly weather conditions.Summer weather in Unalaska
The temperature during the summer in Unalaska hovers around a pleasant 50.5°F (10.3°C) to 53.2°F (11.8°C). The peak daylight can reach a maximum of 17 hours during this period. The humidity in the summer months is relatively higher, reaching up to 91% while the region receives less rainfall, with June being the driest month.Autumn weather in Unalaska
Unalaska during autumn witnesses temperatures gradually dipping from a high of 50°F (10°C) in September down to 37°F (2.8°C) in November. This period also experiences a decrease in daylight from 12.7 hours to 8.6 hours. Rainfall and relative humidity increase substantially, with October receiving the highest rainfall of 3.62" (92mm).Winter weather in Unalaska
Winter in Unalaska is characterized by sub-40°F (-40°C) temperatures and an average snowfall of 4.17" (106mm) in December. The scarcity of daylight, with an average of 7.5 hours in December, combined with limited sunshine of 2 hours, makes the season quite cold and dark. The wind speed also peaks at 16.5mph (26.6km/h), making winter truly felt in this part of Alaska.Weather in January
Kicking off the year, Unalaska, Alaska experiences a surge in snowfall with an impressive 6.97" (177mm) falling on average, making January a peak month for snow enthusiasts. The cold temperatures and the snow are accompanied by low daylight hours presenting typically Alaskan winter conditions. Weather in January »Weather in February
With February comes a slight decrease in snowfall and marginally higher temperatures compared to January, signaling the gradual end of the peak winter season in Unalaska. The persistent chill from icy winds and surfaces, combined with the snowy landscape, maintains the winter feel. Weather in February »Weather in March
Weather in Unalaska during March sees the onset of spring with clear indicators like reduced snowfall, a substantial increase in daylight hours, and a slight elevation of average temperatures. The sea temperature remains pretty much steady, not contributing much to any major weather change. Weather in March »Weather in April
April's weather marks a noticeable transition from winter to spring in Unalaska with temperatures gradually rising to high 30s°F and low rainfall of 2.44" (62mm). The increased daylight hours encourage outdoor activities while the expanded sunshine length adds a warming effect. Weather in April »Weather in May
In May, Unalaska feels a stronger flow of spring warmth with the average high temperature rising to over 40°F (4.4°C). The snowfall disappears completely, replaced by precipitation at other times. The increased daylight hours and sunshine duration add to a more comfortable and pleasant environment. Weather in May »Weather in June
June reveals a more pleasant profile of weather in Unalaska, reflecting a clear summer onset with the average high temperatures climbing until they hit the mid-40s°F. The daylight hours reach their zenith, emphasizing the arrival of the Alaskan summer. Weather in June »Weather in July
The heart of summer in July treats Unalaska with the warmest temperatures of the year, peaking at an average high of 53.2°F (11.8°C), coinciding with a lower rainfall value of 1.85" (47mm). The prevailing summer weather also exhibits longer daylight hours, although slightly fewer than in June. Weather in July »Weather in August
Unalaska's weather in August retains much of its summer characteristics, with the temperature remaining similar to July's, although a slight increase in rainfall to 2.56" (65mm) is noticeable. The humidity diminishes allowing for slightly drier conditions than in July. Weather in August »Weather in September
Come September, the summer heat in Unalaska starts to ease off, reflected in the minor decrease in average temperatures, signalling the onset of fall. Wind speeds climb higher, introducing a fresh breeze into the atmosphere. The cloud cover maintains the uniformity, not affecting the overall visibility. Weather in September »Weather in October
October speaks volumes about the shift towards colder weather in Unalaska with a further decrease in temperature. This month rings in the colder half of the year with an increase in rainfall to 3.62" (92mm), coupled with the reemergence of snowfall, albeit merely 0.12" (3mm). Weather in October »Weather in November
November in Unalaska welcomes winter with significant evidence of snowfall averaging 2.83" (72mm). The average low temperature continues to decrease, setting the stage for a full-fledged winter. The noticeably shorter daylight hours and minimal sunshine duration contributes to a very cold environment. Weather in November »Weather in December
December in Unalaska exhibits full-blown winter characteristics with the lowest average high temperature and the highest rainfall rate of 4.21" (107mm). The snowfall reaches its second-highest point at 5.43" (138mm). The chilling winds continue to blow at high speeds and daylight hours touch their yearly low point. Weather in December »Updated: Jun 22, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Throughout the year, there are 198.8 rainfall days, and 33.78" (858mm) of precipitation is accumulated.
Months with snowfall are January through May, October through December.
The month with the most snowfall is January, when snow falls for 14.2 days and typically aggregates up to 6.97" (177mm) of snow.
In Unalaska, during the entire year, snow falls for 78.3 days and aggregates up to 30.39" (772mm) of snow.
February and March, with an average ocean temperature of 38.8°F (3.8°C), are months with the coldest seawater.
February through April and November, with an average maximum UV index of 1, are months with the lowest UV index in Unalaska.
March, with its high-temperature average of 34.7°F (1.5°C) and a low-temperature average of 30.7°F (-0.7°C), is the coldest month.
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from AKST to AKDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from AKDT to AKST.
June through September are months without snowfall.
The month with the longest days is June, with an average of 17h and 0min of daylight.
June has the most sunshine of the year in Unalaska, with an average of 5.8h of sunshine.
With an average relative humidity of 91%, July is the most humid month.
July is the month with the least rainfall. Rain falls for 19.2 days and accumulates 1.85" (47mm) of precipitation.
July and August, with an average maximum UV index of 3, are months with the highest UV index.
Unalaska's warmest month, August, registers temperatures that range from a high of 53.2°F (11.8°C) to a low of 49.6°F (9.8°C).
August is the month with the warmest seawater in Unalaska, with an average ocean temperature of 50.2°F (10.1°C).
The months with the lowest humidity are November and December, with an average relative humidity of 80%.
December is the month with the most rainfall. Rain falls for 15.3 days and accumulates 4.21" (107mm) of precipitation.
With an average of 7h and 30min of daylight, December has the shortest days of the year.
The month with the least sunshine is December, with an average of 2h of sunshine.
Average temperature
Unalaska, AK
The warmest month (with the highest average high temperature) is August (53.2°F).
The month with the lowest average high temperature is March (34.7°F).
The month with the highest average low temperature is August (49.6°F).
The coldest month (with the lowest average low temperature) is March (30.7°F).
Average pressure
Unalaska, AK
- Average pressure in January:
29.5"Hg - Average pressure in February:
29.66"Hg - Average pressure in March:
29.77"Hg - Average pressure in April:
29.72"Hg - Average pressure in May:
29.84"Hg - Average pressure in June:
29.88"Hg
- Average pressure in July:
29.98"Hg - Average pressure in August:
29.92"Hg - Average pressure in September:
29.79"Hg - Average pressure in October:
29.63"Hg - Average pressure in November:
29.69"Hg - Average pressure in December:
29.52"Hg
The month with the highest atmospheric pressure is July (29.98"Hg).
The month with the lowest atmospheric pressure is January (29.5"Hg).
Average wind speed
Unalaska, AK
- Average wind speed in January:
15.9mph - Average wind speed in February:
15.8mph - Average wind speed in March:
14.7mph - Average wind speed in April:
14.4mph - Average wind speed in May:
10.8mph - Average wind speed in June:
9.6mph
- Average wind speed in July:
9.1mph - Average wind speed in August:
9.6mph - Average wind speed in September:
12.9mph - Average wind speed in October:
15.2mph - Average wind speed in November:
16.5mph - Average wind speed in December:
16.5mph
The windiest months (with the highest average wind speed) are November and December (16.5mph).
The calmest month (with the lowest average wind speed) is July (9.1mph).
Average humidity
Unalaska, AK
The month with the highest relative humidity is July (91%).
The months with the lowest relative humidity are November and December (80%).
Average rainfall
Unalaska, AK
- Average rainfall in January:
3.39" - Average rainfall in February:
3.03" - Average rainfall in March:
2.28" - Average rainfall in April:
2.44" - Average rainfall in May:
2.36" - Average rainfall in June:
2.13"
- Average rainfall in July:
1.85" - Average rainfall in August:
2.56" - Average rainfall in September:
2.72" - Average rainfall in October:
3.62" - Average rainfall in November:
3.19" - Average rainfall in December:
4.21"
The wettest month (with the highest rainfall) is December (4.21").
The driest month (with the least rainfall) is July (1.85").
Average rainfall days
Unalaska, AK
- Average rainfall days in January:
12.6 days - Average rainfall days in February:
11.1 days - Average rainfall days in March:
12.1 days - Average rainfall days in April:
15.8 days - Average rainfall days in May:
18.8 days - Average rainfall days in June:
17.2 days
- Average rainfall days in July:
19.2 days - Average rainfall days in August:
17.8 days - Average rainfall days in September:
19.8 days - Average rainfall days in October:
21.8 days - Average rainfall days in November:
17.3 days - Average rainfall days in December:
15.3 days
The month with the highest number of rainy days is October (21.8 days).
The month with the least rainy days is February (11.1 days).
Average snowfall
Unalaska, AK
- Average snowfall in January:
6.97" - Average snowfall in February:
5.59" - Average snowfall in March:
4.17" - Average snowfall in April:
4.09" - Average snowfall in May:
1.18" - Average snowfall in June:
0"
The month with the highest snowfall is January (6.97").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days
Unalaska, AK
- Average snowfall days in January:
14.2 days - Average snowfall days in February:
14 days - Average snowfall days in March:
13.2 days - Average snowfall days in April:
12.2 days - Average snowfall days in May:
4.1 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0 days - Average snowfall days in October:
0.7 days - Average snowfall days in November:
7 days - Average snowfall days in December:
12.9 days
The month with the highest number of snowfall days is January (14.2 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average sea temperature
Unalaska, AK
The best month for swimming (with the highest average sea temperature) is August (50.1°F).
The coldest month (with the lowest average sea temperature) is February (38.8°F).
Average daylight / Average sunshine
Unalaska, AK
- Average daylight in January:
8h and 6min - Average daylight in February:
9h and 48min - Average daylight in March:
11h and 54min - Average daylight in April:
14h and 6min - Average daylight in May:
16h and 0min - Average daylight in June:
17h and 0min
- Average daylight in July:
16h and 30min - Average daylight in August:
14h and 48min - Average daylight in September:
12h and 42min - Average daylight in October:
10h and 30min - Average daylight in November:
8h and 36min - Average daylight in December:
7h and 30min
The month with the longest days is June (Average daylight: 17h and 0min).
The month with the shortest days is December (Average daylight: 7h and 30min).
- Average sunshine in January:
2h and 36min - Average sunshine in February:
3h and 6min - Average sunshine in March:
3h and 54min - Average sunshine in April:
4h and 24min - Average sunshine in May:
5h and 12min - Average sunshine in June:
5h and 48min
- Average sunshine in July:
4h and 54min - Average sunshine in August:
5h and 30min - Average sunshine in September:
4h and 42min - Average sunshine in October:
4h and 30min - Average sunshine in November:
3h and 6min - Average sunshine in December:
2h and 0min
The month with the most sunshine is June (Average sunshine: 5h and 48min).
The month with the least sunshine is December (Average sunshine: 2h and 0min).
Average sunshine days
Unalaska, AK
- Average sunshine days in January:
4.5 days - Average sunshine days in February:
4.9 days - Average sunshine days in March:
6 days - Average sunshine days in April:
3.8 days - Average sunshine days in May:
7.8 days - Average sunshine days in June:
8.8 days
- Average sunshine days in July:
8.6 days - Average sunshine days in August:
9.7 days - Average sunshine days in September:
6.9 days - Average sunshine days in October:
5.4 days - Average sunshine days in November:
4.9 days - Average sunshine days in December:
4.1 days
The month with the most sunshine days is August (9.7 days).
The month with the least sunshine days is April (3.8 days).
Average UV index
Unalaska, AK
The months with the highest UV index are July and August (UV index 3).
The months with the lowest UV index are February, March, April and November (UV index 1).
Average cloud cover
Unalaska, AK
The month with the most cloud cover is July (Cloud cover 74).
The months with the least cloud cover are September and October (Cloud cover 66).
Average visibility
Unalaska, AK
The months with the highest visibility are May, June, August, September, October and November (6mi).
The months with the lowest visibility are January, February, March, April, July and December (5mi).
