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Monthly climate in Unalaska, Alaska, United States

Last updated: March 2, 2024

Under the Köppen–Geiger climate classification Unalaska features a ice cap climate ET). Temperatures typically range between -1 °C (30 °F) and 11 °C (51 °F) through the year, but rarely can drop to -13 °C (10 °F) or can rise to as high as 19 °C (67 °F). The average annual precipitation amounts to about 1345 mm (52.9 inches) and receives 203 rainy days on the 1 mm (0.04 inches) threshold annually. Unalaska enjoys an average of 1900 hours of sunshine throughout the year, and daylight varies from 7 hours 28 minutes to 17 hours 0 minutes per day.

Monthly average temperatures in Unalaska, Alaska, United States §

The warmest months in Unalaska are July, August and September, with daily mean temperatures ranging from 9 to 11 °C (48 - 51 °F) throughout the day. The coldest temperatures usually occur in January, March and December, when daily mean temperatures range from -1 to 0 °C (30 - 32 °F) throughout the day. On average each year, Unalaska experiences 0 days above 25 °C (77.0 °F) and 112 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Unalaska, Alaska, United States. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to June 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Maximum 6°C
(42°F)		 6°C
(43°F)		 6°C
(42°F)		 9°C
(48°F)		 10°C
(50°F)		 12°C
(54°F)		 17°C
(63°F)		 19°C
(67°F)		 17°C
(63°F)		 12°C
(54°F)		 9°C
(48°F)		 8°C
(47°F)
Mean maximum 5°C
(41°F)		 5°C
(41°F)		 5°C
(40°F)		 7°C
(44°F)		 9°C
(48°F)		 11°C
(53°F)		 16°C
(61°F)		 17°C
(63°F)		 14°C
(57°F)		 11°C
(52°F)		 8°C
(46°F)		 7°C
(45°F)
Average high 0°C
(33°F)		 2°C
(36°F)		 2°C
(35°F)		 3°C
(39°F)		 6°C
(43°F)		 9°C
(49°F)		 12°C
(53°F)		 13°C
(55°F)		 10°C
(51°F)		 7°C
(45°F)		 4°C
(40°F)		 2°C
(35°F)
Daily mean -1°C
(30°F)		 1°C
(33°F)		 -0°C
(32°F)		 2°C
(35°F)		 4°C
(40°F)		 7°C
(46°F)		 10°C
(50°F)		 11°C
(51°F)		 9°C
(48°F)		 5°C
(42°F)		 2°C
(37°F)		 -0°C
(32°F)
Average low -3°C
(27°F)		 -1°C
(30°F)		 -2°C
(28°F)		 -0°C
(32°F)		 2°C
(37°F)		 6°C
(43°F)		 8°C
(47°F)		 9°C
(48°F)		 7°C
(45°F)		 4°C
(39°F)		 1°C
(34°F)		 -2°C
(28°F)
Mean minimum -8°C
(18°F)		 -7°C
(20°F)		 -6°C
(21°F)		 -5°C
(23°F)		 -1°C
(31°F)		 3°C
(38°F)		 6°C
(43°F)		 6°C
(43°F)		 3°C
(38°F)		 -1°C
(31°F)		 -4°C
(25°F)		 -9°C
(17°F)
Minimum -10°C
(14°F)		 -13°C
(10°F)		 -8°C
(18°F)		 -9°C
(17°F)		 -1°C
(30°F)		 2°C
(36°F)		 5°C
(41°F)		 5°C
(40°F)		 2°C
(36°F)		 -3°C
(27°F)		 -8°C
(18°F)		 -11°C
(13°F)

Compare climate in Unalaska with other places

Compare temperature, precipitation, sunshine, UV index in Unalaska, Alaska, United States with other places around the world.

Monthly average precipitation in Unalaska, Alaska, United States §

Unalaska usually has the most precipitation in February, October and December, with an average of 20 rainy days and 153 mm (6.0 inches) of precipitation per month. The driest months in Unalaska are March, July and August. On average, 82 mm (3.2 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Unalaska, Alaska, United States. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to January 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Average precipitation mm (inches) 95 (3.8) 157 (6.2) 92 (3.6) 99 (3.9) 115 (4.5) 100 (3.9) 65 (2.6) 89 (3.5) 117 (4.6) 147 (5.8) 113 (4.5) 157 (6.2)
Average precipitation days (≥ 1 mm) 14 20 14 19 22 14 12 16 17 20 15 20

Monthly sunshine hours in Unalaska, Alaska, United States §

The sunniest months in Unalaska are May, June and August, when the sun shines an average of 7 hours 4 minutes a day. Least sunny months in Unalaska: January, November and December receive an average of 2 hours 43 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Unalaska, Alaska, United States. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2017 to January 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Mean monthly sunshine hours 75 101 170 185 243 210 176 196 191 173 94 80
Mean daily daylight hours 8h 3m 9h 48m 11h 56m 14h 6m 16h 0m 17h 0m 16h 26m 14h 42m 12h 35m 10h 26m 8h 30m 7h 28m

Solar UV radiation in Unalaska, Alaska, United States §

Unalaska experiences the highest level of ultraviolet (UV) radiation in June, July and August, when the maximum UV index can reach values of 7 - 8, which corresponds to the High / Very High category of sun exposure. January, February and December are in the Low exposure category. In these months, the maximum values of the UV index do not exceed 2. For more detailed information, check out our hourly Unalaska UV Index data.

Average daily maximum UV levels by month for Unalaska, Alaska, United States. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2022 to January 2023.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
UV Index (month maximum) 1 2 3 5 6 7 8 8 5 3 2 1

Detailed Monthly Weather Insights for Unalaska, Alaska, United States

Discover in-depth weather details for every month in Unalaska. Click through the links below for comprehensive overviews of temperature trends, precipitation levels, sunshine hours, and solar UV radiation specifics. Whether planning a visit or simply curious about Unalaska's climate nuances, these monthly breakdowns provide the information you need for an informed understanding of what to expect throughout the year.

Each link leads to a detailed account of the typical weather conditions for that month, providing both locals and tourists with vital information to plan their daily activities, wardrobe, and travel itineraries accordingly.