December weather forecast
Portland, OR

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A colorful autumn view of the outline of Portland City, Oregon, USA
A colorful autumn view of the outline of Portland City, Oregon, USA

Weather in December

December welcomes the winter season in full swing in Portland. The colder month brings 4.53" (115mm) of rainfall, the highest monthly average for the year. Accompanied by cooler winds, the temperatures add to the winter chill. Despite shorter days, the city brims with holiday cheer. Decked up in festive lights, Portland embraces winter with panache, promising an array of indoor and outdoor activities.

Temperature

The coldest temperatures occur during December, when averages reach a peak of 44.1°F (6.7°C) and a low of 34.7°F (1.5°C).

Humidity

January, February and December, with an average relative humidity of 83%, are the most humid months.

Rainfall

December is the month with the most rainfall. Rain falls for 18.5 days and accumulates 4.53" (115mm) of precipitation.

Snowfall

Months with snowfall in Portland are January through March, November and December. In Portland, in December, snow falls for 0.8 days, with typically accumulated 0.28" (7mm) of snow. Throughout the year, there are 6.4 snowfall days, and 3.94" (100mm) of snow is accumulated.

Daylight

With an average of 8h and 48min of daylight, December has the shortest days of the year.
On the first day of December, sunrise is at 7:31 am and sunset at 4:28 pm. On the last day of the month, sunrise is at 7:50 am and sunset at 4:37 pm PST.

Sunshine

The average sunshine in December is 4.3h.

UV index

The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2. A UV Index value of 2, and less, symbolizes a low threat to health from unprotected exposure to Sun's UV rays for average individuals.
Note: The daily high UV index of 2 during December translates into the following recommendations:
Sun exposure does not present considerable issues for many, yet infants, fair-skinned people, and children necessitate constant protection. To prevent harmful UV exposure, minimize direct contact with the Sun around midday. A hat with a broad brim is indispensable, filtering out up to half of UV rays. Be attentive! The reflective property of snow can nearly double the Sun's UV radiation.

Frequently asked questions

What is the coldest month?

December, with its high-temperature average of 44.1°F (6.7°C) and a low-temperature average of 34.7°F (1.5°C), is the coldest month.

Is December cold?

In December, the average high-temperature and low-temperature are 44.1°F (6.7°C) and 34.7°F (1.5°C) respectively. In August, the average heat index (a.k.a. 'felt air temperature', 'apparent temperature'), which represents the influence of relative humidity on air temperature, is appraised at 84.2°F (29°C).

What are the most humid months?

The months with the highest humidity are January, February and December, with an average relative humidity of 83%.

What is the average humidity in December?

The average relative humidity in December is 83%.

What is the rainiest month?

December is the month with the most rainfall. Rain falls for 18.5 days and accumulates 4.53" (115mm) of precipitation.

How much does it rain in December?

In Portland, Oregon, during December, the rain falls for 18.5 days and regularly aggregates up to 4.53" (115mm) of precipitation.

How much does it snow in December?

In Portland, Oregon, in December, snow falls for 0.8 days, with typically accumulated 0.28" (7mm) of snow.

What is the month with the shortest days?

December has the shortest days of the year, with an average of 8h and 48min of daylight.

How many hours of daylight does Portland have in December?

The average day length in December is 8h and 46min.

When is the sunrise / sunset in December?

In December, on the first day of the month, sunrise is at 7:31 am and sunset at 4:28 pm. On the last day of the month, sunrise is at 7:50 am and sunset at 4:37 pm PST.

How many hours of sunshine does Portland have in December?

In Portland, the average sunshine duration in December is 4.3h.

What is the month with the lowest UV index?

The months with the lowest UV index in Portland are January, February, November and December, with an average maximum UV index of 2.

What is the UV index intensity in December in Portland?

In Portland, the average daily maximum UV index in December is 2. A UV Index reading of 2, and below, represents a minimal hazard to health from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Portland, OR

Average temperature in December - Portland, OR
  • Average high temperature in December: 44.1°F

The warmest month (with the highest average high temperature) is August (81.5°F).
The month with the lowest average high temperature is December (44.1°F).

  • Average low temperature in December: 34.7°F

The month with the highest average low temperature is August (55°F).
The coldest month (with the lowest average low temperature) is December (34.7°F).

Average pressure in December
Portland, OR

Average pressure in December - Portland, OR
  • Average pressure in December: 30.1"Hg

The month with the highest atmospheric pressure is January (30.12"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).

Average wind speed in December
Portland, OR

Average wind speed in December - Portland, OR
  • Average wind speed in December: 5.5mph

The windiest month (with the highest average wind speed) is January (5.8mph).
The calmest month (with the lowest average wind speed) is August (3.9mph).

Average humidity in December
Portland, OR

Average humidity in December - Portland, OR
  • Average humidity in December: 83%

The months with the highest relative humidity are January, February and December (83%).
The month with the lowest relative humidity is August (63%).

Average rainfall in December
Portland, OR

Average rainfall in December - Portland, OR
  • Average rainfall in December: 4.53"

The wettest month (with the highest rainfall) is December (4.53").
The driest month (with the least rainfall) is July (0.31").

Average rainfall days in December
Portland, OR

Average rainfall days in December - Portland, OR
  • Average rainfall days in December: 18.5 days

The month with the highest number of rainy days is March (20.4 days).
The month with the least rainy days is July (4.9 days).

Average snowfall in December
Portland, OR

Average snowfall in December - Portland, OR
  • Average snowfall in December: 0.28"

The month with the highest snowfall is March (1.5").
The months with the least snowfall are April, May, June, July, August, September and October (0").

Average snowfall days in December
Portland, OR

Average snowfall days in December - Portland, OR
  • Average snowfall days in December: 0.8 days

The month with the highest number of snowfall days is February (2.3 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

Average daylight in December /
Average sunshine in December
Portland, OR

Average daylight in December / Average sunshine in December - Portland, OR
  • Average daylight in December: 8h and 5min

The month with the longest days is June (Average daylight: 15h and 36min).
The month with the shortest days is December (Average daylight: 8h and 48min).

  • Average sunshine in December: 4h and 2min

The month with the most sunshine is August (Average sunshine: 10h and 54min).
The month with the least sunshine is January (Average sunshine: 4h and 6min).

Average sunshine days in December
Portland, OR

Average sunshine days in December - Portland, OR
  • Average sunshine days in December: 10.5 days

The months with the most sunshine days are July and August (23.8 days).
The month with the least sunshine days is March (8.3 days).

Average UV index in December
Portland, OR

Average UV index in December - Portland, OR
  • Average UV index in December: 2

The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).

Average cloud cover in December
Portland, OR

Average cloud cover in December - Portland, OR
  • Average cloud cover in December: 56

The month with the most cloud cover is February (Cloud cover 58).
The month with the least cloud cover is August (Cloud cover 23).

Average visibility in December
Portland, OR

Average visibility in December - Portland, OR
  • Average visibility in December: 5mi

The months with the highest visibility are July, August and September (6mi).
The months with the lowest visibility are January, February, March, April, May, June, October, November and December (5mi).

Portland, Oregon, USA

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