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.
|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.
|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.
|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.
|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.
|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 Time||1 am||4 am||7 am||10 am||1 pm||4 pm||7 pm||10 pm|
|9.5 mph||December wind speed average||15.3 kph|
December is windier than most other months in Portland.
|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.