December weather forecastUnalaska, AK
December
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. The relative humidity is on the upward trend when compared to November, adding to the overall chilly feel. The sea temperature continues to drop, falling in line with the ongoing winter season, rounding off Unalaska's diverse weather pattern.Temperature
Unalaska's weather in December, with an average high-temperature of a still cold 37°F (2.8°C), subtly shifts from November's 40.6°F (4.8°C). A modest dip in temperatures to an average of 33.8°F (1°C) is observed throughout Unalaska's December nights.Humidity
The months with the lowest humidity are November and December, with an average relative humidity of 80%.Rainfall
December is the month with the most rainfall. Rain falls for 15.3 days and accumulates 4.21" (107mm) of precipitation.Snowfall
Months with snowfall are January through May, October through December. In December, it is snowing for 12.9 days. Throughout December, 5.43" (138mm) of snow is accumulated. Throughout the year, there are 78.3 snowfall days, and 30.39" (772mm) of snow is accumulated.Ocean temperature
In Unalaska, the average seawater temperature in December is 41.5°F (5.3°C).Note: With the appropriate swimsuit, one can swim in 41.5°F (5.3°C) even if temperatures dip below 50°F (10°C); otherwise, be ready for cold shock and breath issues. A fleeting swim around 55.4°F (13°C) is distressing.
Daylight
December has the shortest days of the year in Unalaska, with an average of 7h and 30min of daylight.On the first day of December, sunrise is at 10:02 am and sunset at 5:48 pm. On the last day of the month, sunrise is at 10:24 am and sunset at 5:54 pm AKST.
Sunshine
December has the least sunshine of the year, with an average of 2h of sunshine.UV index
The average daily maximum UV index in December in Unalaska is 2. A UV Index value of 2, and less, symbolizes a low health risk from unprotected exposure to Sun's UV rays for the average person.Note: In December, a regular UV index of 2 translates into these guidelines:
People with sensitive skin, children, and babies should always be protected from prolonged sun exposure. Solar radiation peaks around mid-day, so it's wise to limit exposure to the Sun at this time. To cut down UV radiation exposure by about half, sport a wide-brim hat. Take careful note! The UV radiation of the Sun can be nearly doubled by snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Unalaska, AK
- Average high temperature in December: 37°F
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).
- Average low temperature in December: 33.8°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 in December
Unalaska, AK
- 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 in December
Unalaska, AK
- 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 in December
Unalaska, AK
- Average humidity in December: 80%
The month with the highest relative humidity is July (91%).
The months with the lowest relative humidity are November and December (80%).
Average rainfall in December
Unalaska, AK
- 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 in December
Unalaska, AK
- 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 in December
Unalaska, AK
- Average snowfall in December: 5.43"
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 in December
Unalaska, AK
- 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 in December
Unalaska, AK
- Average sea temperature in December: 41.5°F
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 in December /
Average sunshine in December
Unalaska, AK
- 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 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 in December
Unalaska, AK
- 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 in December
Unalaska, AK
- Average UV index in December: 2
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 in December
Unalaska, AK
- Average cloud cover in December: 72
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 in December
Unalaska, AK
- Average visibility in December: 5mi
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).
