Portland Weather in December

December is the time for extreme weather in Portland, Oregon. This is the coldest, cloudiest, rainiest and snowiest month of the year.

This page gives detailed information on the typical December temperature, precipitation, sun, humidity, wind and storms for Portland. The numbers here are historical averages based on climate data gathered near the Portland International Airport, located a few miles from downtown Portland.

Temperature Weather iconTemperature

46 °F December average high 8 °C
36 °F December average low 2 °C

December is the coldest month for Portland, with the lowest overall temperatures for the year beginning on the 17th. From that date until early January the daily highs average 45 degrees Fahrenheit (7 degrees Celsius) while lows are 36 °F (2 °C).

27 days 40 °F max. or more (4 °C)
8 days 32 °F min. or less (0 °C)

Portland averages 8 days in December when the thermometer reaches into the 50s °F (over 10 °C). Temperatures above 60 °F (16 °C) occur in December, but not every year.

In some years, the thermometer dips below 20 °F (-8 °C) at night. But December does not normally get as cold as 10 °F (-12 °C). Typically once this month the mercury remains below freezing for the entire day.

Rainy Weather iconPrecipitation

7.0 in total precipitation 177 mm
20 days of rain or snowfall

Half the time, the Portland receives 4.5 to 8.4 inches (115 to 212 mm) of precipitation in December. One in four years has drier weather, while another one in four is wetter.

Snowy Weather iconSnow

1.4 in total snowfall 4 cm
1 day with new snow

Most years, Portland receives no fresh snow for the month. In one out of four Decembers, the city gets 1 inch (2.5 cm) or more of fresh snow.

Portland has two days in December, on average, when the snow accumulated on the ground amounts to an inch (2.5 cm) or more.

Sunny Weather iconSun

23 % sunshine
2 days clear skies

The sun's rays reach the ground in Portland during 23 percent of daylight hours on average in December, for a total of 63 hours in the month. Typically on 2 days this month the sky is mainly clear, with at most 30 percent cloud cover.

Sunlight in December at Portland averages 8 hours and 46 minutes a day. The shortest days of the year, from around December 18th to 24th, last 8 hours and 42 minutes from sunrise to sunset.

Humid Weather iconHumidity

83 % December average humidity

The relative humidity in Portland during December usually peaks at 86 percent in the morning then drops to 77 percent by early afternoon. December is the most humid time of the year for Portland.

Local Time1 am4 am7 am10 am1 pm4 pm7 pm10 pm
Humidity % 85 86 86 83 77 78 82 84

Windy Weather iconWind

9.5 mph December wind speed average 15.3 kph

December is windier than most other months in Portland.

Stormy Weather iconStorms

5 days rainfall of 0.5 inches (13 mm) or more
0 days with thunderstorms in December

December is Portland's stormiest time of year. One or two days this month receive an inch (25 mm) or more of rain.


The weather data here are long-term averages provided by the US National Centers for Environmental Information (NCEI). Temperature and precipitation are 1991-2020 normals while humidity and thunderstorms are 1961-1990 normals.

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