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December Weather in Portland, United States

Last updated: June 24, 2025

In December, the average temperature in Portland, United States is a comfortable 16°C (61°F), with a chilly minimum of 1°C (34°F) and a pleasant maximum of 27°C (81°F). Expect 47 mm (1.9 in) of precipitation spread over about 5 days, and prepare for an average humidity level of around 80%.

December Temperature in Portland

In December in Portland, the average temperature is 16°C (61°F). Maximums can reach 27°C (81°F), while minimums can drop as low as 1°C (34°F). This varied climate makes Portland an ideal destination for travelers seeking both warm and cool experiences.

December Weather in Portland: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Portland, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Portland, December typically has an average temperature of 16°C (61°F), with highs reaching up to 27°C (81°F) and lows dropping to around 1°C (34°F).
JanFebMarAprMayJunJulAugSepOctNovDec586068737983848482756661
Data source: Temperature data for Portland generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

December Precipitation in Portland

In Portland in December, the precipitation amount is 47 mm (1.9 in) spread over a duration of 5 days.

December Precipitation Trends in Portland

The chart displays monthly precipitation patterns in Portland, with values for each month alongside December’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how December’s conditions compare to those of other months. In Portland, December typically receives around 47 mm (1.9 inches) of precipitation spread over approximately 5 days.
JanFebMarAprMayJunJulAugSepOctNovDec3931524413813610181141775247
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Portland

In Portland in December, humidity is 80%. With an average temperature of 16°C (61°F), this humidity feels like a warm blanket wrapped around you, making sightseeing a sweat-inducing challenge but also lending a lush vibrancy to the surroundings that can enhance your travel experience.

December Average Humidity in Portland

This chart illustrates the average monthly humidity levels in Portland, with December’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In December, average humidity in Portland is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec78%82%79%82%81%77%78%78%79%77%78%80%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Portland

In Portland in December, the maximum UV index reaches 5, which corresponds to a moderate Exposure Category. Under these conditions, the estimated time to burn is approximately 30 minutes. For more details, you can check the Hourly UV Index in Portland.

Maximum UV Index Levels in Portland for December

The chart shows the monthly maximum UV Index (UVI) for Portland in December, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In December, the maximum UV index in Portland typically reaches 5, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec589111112121211975
Data source: Portland December UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How December Weather in Portland Compares to Other Months

Weather in Portland varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Portland, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Portland, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather14°C (58°F)39 mm (1.5 inches)78%moderate
February Weather16°C (60°F)31 mm (1.2 inches)82%very high
March Weather20°C (68°F)52 mm (2.1 inches)79%very high
April Weather23°C (73°F)44 mm (1.7 inches)82%extreme
May Weather26°C (79°F)138 mm (5.4 inches)81%extreme
June Weather28°C (83°F)136 mm (5.4 inches)77%extreme
July Weather29°C (84°F)101 mm (4.0 inches)78%extreme
August Weather29°C (85°F)81 mm (3.2 inches)78%extreme
September Weather28°C (82°F)141 mm (5.6 inches)79%extreme
October Weather24°C (75°F)77 mm (3.0 inches)77%very high
November Weather19°C (66°F)51 mm (2.0 inches)78%high
December Weather16°C (61°F)47 mm (1.9 inches)80%moderate

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