Weather and climate in Unalaska (Alaska)

Unalaska has a subpolar oceanic climate, with very cold winters and very cool summers. The sky is often cloudy.
Unalaska is the largest village in the Aleutian Islands and is located on Unalaska Island, which belongs to the Fox Islands group, at 53 degrees north latitude.
Within the island are mountains, which remain snow capped above 700 metres (2,300 feet). The highest peak is Makushin volcano, 2,036 meters (6,680 ft) high.
Nearby, on the small island of Amaknak, is Dutch Harbor.
Precipitation is abundant, moreover it is very frequent, especially in autumn and winter. On average, 207 cm (81.5 in) of snow fall per year. It usually snows from October to April.
Even though the temperatures are not very low, the wind increases the sensation of cold, especially from October to April, when it often blows moderately or strongly.
In winter it often snows, but since the temperature can go above freezing, there are times when it can rain or rain mixed with snow can fall. There are cold periods, when the temperature remains below freezing even during the day, but it rarely drops below -10 °C (14 °F). In January 1989 it dropped to -14 °C (7 °F).
The summer is very cool, with frequent rains. Sometimes it can get quite cold even in these months, with highs of 10/12 °C (50/54 °F).
There may also be pleasant periods, which last a few days, in which the temperature reaches around 18/20 °C (64/68 °F).

Best Time

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The best time to visit Unalaska is the summer, in July and August, since they are the mildest months. However, you must take into account cloudy skies, some rain and a bit of cold. Therefore, it is advisable to bring a jacket and a sweater even in the height of summer.

Unalaska - Climate data

The average temperature of the coldest month (January) is of 0.6 °C (33.0 °F), that of the warmest month (August) is of 12.0 °C (53.7 °F). Here are the average temperatures.
Precipitation amounts to 1525 millimeters (60 inches) per year: it is therefore abundant. It ranges from 60 mm (2.4 in) in the driest month (July) to 200 mm (7.9 in) in the wettest ones (October, December) Here is the average precipitation.
The sea temperature ranges from 4 °C (39 °F) in February, March to 10.5 °C (51 °F) in August. Here are the average sea temperatures.

Unalaska - Weather by month

Based on the period 1991-2020

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January, the coldest month of the year, is generally a cold month. The average temperature is of 0.6 °C (33 °F), with a minimum of -1.8 °C (28.8 °F) and a maximum of 2.9 °C (37.2 °F).
On the coldest nights of the month, the temperature usually drops to around -6.5 °C (20 °F).
On the warmest days of the month, the temperature usually reaches around 7 °C (44.5 °F).
Precipitation amounts to 170 mm (6.7 in), distributed over 22 days.
The day lasts on average 8 hours and 5 minutes.
The average humidity is 74%. Hence, the air is normally humid.
The average wind speed is 20 kph (13 mph).
The average sea temperature is of 4.5 °C (40 °F). Therefore, the sea is very cold for swimming.

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February is generally a cold month. The average temperature is of 1.2 °C (34 °F), with a minimum of -1.4 °C (29.5 °F) and a maximum of 3.7 °C (38.7 °F).
On the coldest nights of the month, the temperature usually drops to around -6.5 °C (20 °F).
On the warmest days of the month, the temperature usually reaches around 8 °C (46 °F).
Precipitation amounts to 130 mm (5.1 in), distributed over 19 days.
The day lasts on average 9 hours and 55 minutes.
The average humidity is 74%. Hence, the air is normally humid.
The average wind speed is 20 kph (12 mph).
The average sea temperature is of 4 °C (39 °F). Therefore, the sea is very cold for swimming.

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March is generally a cold month. The average temperature is of 1.1 °C (34 °F), with a minimum of -1.6 °C (29.1 °F) and a maximum of 3.8 °C (38.8 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -6 °C (21.5 °F).
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 8 °C (47 °F).
Precipitation amounts to 120 mm (4.7 in), distributed over 19 days.
The day lasts on average 12 hours and 0 minutes.
The average humidity is 73%. Hence, the air is normally humid.
The average wind speed is 19 kph (12 mph).
The average sea temperature is of 4 °C (39 °F). Therefore, the sea is very cold for swimming.

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April is generally a cold month. The average temperature is of 2.8 °C (37 °F), with a minimum of 0.3 °C (32.5 °F) and a maximum of 5.4 °C (41.7 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -3.5 °C (26 °F).
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 9.5 °C (48.5 °F).
Precipitation amounts to 90 mm (3.5 in), distributed over 18 days.
The day lasts on average 14 hours and 10 minutes.
The average humidity is 74%. Hence, the air is normally humid.
The average wind speed is 19 kph (12 mph).
The average sea temperature is of 4.5 °C (39.5 °F). Therefore, the sea is very cold for swimming.

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May is generally a quite cold month. The average temperature is of 5.6 °C (42 °F), with a minimum of 3 °C (37.4 °F) and a maximum of 8.2 °C (46.8 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 0 °C (32 °F).
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 11.5 °C (52.5 °F).
Precipitation amounts to 105 mm (4.1 in), distributed over 18 days.
The day lasts on average 16 hours and 5 minutes. So the days are long.
The average humidity is 76%. Hence, the air is normally humid.
The average wind speed is 16 kph (10 mph).
The average sea temperature is of 5.5 °C (41.5 °F). Therefore, the sea is very cold for swimming.

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June is generally a mild month. The average temperature is of 8.6 °C (47 °F), with a minimum of 5.8 °C (42.4 °F) and a maximum of 11.3 °C (52.3 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 3 °C (38 °F).
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 15.5 °C (60 °F).
Precipitation amounts to 65 mm (2.6 in), distributed over 15 days.
The day lasts on average 17 hours and 0 minutes. So the days are very long. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
The average humidity is 79%. Hence, the air is normally humid.
The average wind speed is 14 kph (9 mph).
The average sea temperature is of 7 °C (45 °F). Therefore, the sea is very cold for swimming.

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July is generally a mild month. The average temperature is of 11.1 °C (52 °F), with a minimum of 8.1 °C (46.6 °F) and a maximum of 14.1 °C (57.4 °F).
On the coldest nights of the month, the temperature usually drops to around 5.5 °C (42 °F).
On the warmest days of the month, the temperature usually reaches around 19.5 °C (67 °F).
Precipitation amounts to 60 mm (2.4 in), distributed over 14 days.
The day lasts on average 16 hours and 25 minutes. So the days are long.
The average humidity is 80%. Hence, the air is normally humid.
The average wind speed is 13 kph (8 mph).
The average sea temperature is of 9 °C (48 °F). Therefore, the sea is very cold for swimming.

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August, the warmest month of the year, is generally a mild month. The average temperature is of 12.0 °C (54 °F), with a minimum of 8.9 °C (48 °F) and a maximum of 15.2 °C (59.4 °F).
On the coldest nights of the month, the temperature usually drops to around 6.5 °C (43.5 °F).
On the warmest days of the month, the temperature usually reaches around 20.5 °C (68.5 °F).
Precipitation amounts to 75 mm (3 in), distributed over 15 days.
The day lasts on average 14 hours and 40 minutes. So the days are long.
The average humidity is 79%. Hence, the air is normally humid.
The average wind speed is 14 kph (9 mph).
The average sea temperature is of 10.5 °C (50.5 °F). Therefore, the sea is very cold for swimming.

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September is generally a mild month. The average temperature is of 9.7 °C (49 °F), with a minimum of 6.8 °C (44.2 °F) and a maximum of 12.6 °C (54.7 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 3.5 °C (38.5 °F).
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 16.5 °C (62 °F).
Precipitation amounts to 145 mm (5.7 in), distributed over 20 days.
The day lasts on average 12 hours and 35 minutes.
The average humidity is 76%. Hence, the air is normally humid.
The average wind speed is 18 kph (11 mph).
The average sea temperature is of 10 °C (50 °F). Therefore, the sea is very cold for swimming.

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October is generally a quite cold month. The average temperature is of 6.2 °C (43 °F), with a minimum of 3.6 °C (38.5 °F) and a maximum of 8.9 °C (48 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 0.5 °C (32.5 °F).
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 13.5 °C (56 °F).
Precipitation amounts to 200 mm (7.9 in), distributed over 25 days.
The day lasts on average 10 hours and 25 minutes.
The average humidity is 73%. Hence, the air is normally humid.
The average wind speed is 20 kph (12 mph).
The average sea temperature is of 8.5 °C (47 °F). Therefore, the sea is very cold for swimming.

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November is generally a cold month. The average temperature is of 3.5 °C (38 °F), with a minimum of 0.7 °C (33.3 °F) and a maximum of 6.3 °C (43.3 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around -2 °C (28 °F).
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 11 °C (51.5 °F).
Precipitation amounts to 170 mm (6.7 in), distributed over 22 days.
The day lasts on average 8 hours and 30 minutes.
The average humidity is 72%. Hence, the air is normally humid.
The average wind speed is 21 kph (13 mph).
The average sea temperature is of 6.5 °C (44 °F). Therefore, the sea is very cold for swimming.

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December is generally a cold month. The average temperature is of 1.6 °C (35 °F), with a minimum of -0.8 °C (30.6 °F) and a maximum of 4.1 °C (39.4 °F).
On the coldest nights of the month, the temperature usually drops to around -5 °C (23 °F).
On the warmest days of the month, the temperature usually reaches around 9.5 °C (49.5 °F).
Precipitation amounts to 200 mm (7.9 in), distributed over 23 days.
The day lasts on average 7 hours and 30 minutes. So the days are short. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
The average humidity is 73%. Hence, the air is normally humid.
The average wind speed is 21 kph (13 mph).
The average sea temperature is of 5.5 °C (42 °F). Therefore, the sea is very cold for swimming.