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 weather for Portland.

You can jump directly to data and descriptions for:

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

45 °F December average high 7 °C
35 °F December average low 2 °C

In most years, Portland averages a daily maximum temperature for December that's between 42 and 48 degrees Fahrenheit (6 to 9 degrees Celsius). The minimum temperature usually falls between 32 and 38 °F (0 to 4 °C).

December is the coldest month overall for Portland and the 22nd to 23rd are its chilliest days. They have daily highs averaging 43.9 °F (6.6 °C) and lows of 34.4 °F (1.3 °C).

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

Portland averages 6 days in December when the thermometer reaches into the 50s °F (over 10 °C). Temperatures above 60 °F (16 °C) occur in December just once a decade.

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

Rainy Weather iconPrecipitation

6.9 in total precipitation 176 mm
20 days of rain or snowfall

December is the rainiest month all year for Portland. Half the time, the city receives 4 to 9 inches (110 to 234 mm) of precipitation in December. One in four years has drier weather, while another one in four is wetter.

Snowy Weather iconSnow

2.0 in total snowfall 5.1 cm
1 day with new snow

Portland is more likely to get snow in December than any other month. Yet most years, Portland receives no fresh snow for the month. In one out of four Decembers, the city gets 2 inches (5 cm) or more of fresh snow.

Portland has just one day 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.

Reference

These weather data are long-term historical averages provided by the National Climatic Data Center of the United States. The temperature and precipitation numbers are 1981-2010 normals while the humidity and thunderstorm statistics are 1961-1990 normals.

Portland Weather
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