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December Weather in Portland, Australia

Last updated: August 22, 2025

In Portland, Australia, the average temperature in December hovers around 19°C (66°F). However, you can expect a temperature range from a cool 5°C (41°F) to a sizzling 37°C (99°F). During this month, precipitation typically amounts to 76 mm (3.0 in) spread over about 10 days, accompanied by an average humidity of 62%. Prepare for a mix of warm days and refreshing showers!

December Temperature in Portland

In December in Portland, the average temperature is 19°C (66°F). Maximums can reach 37°C (99°F) and minimums can be as low as 5°C (41°F). This makes it an ideal time to visit, offering pleasant days and cooler evenings for travelers.

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 19°C (66°F), with highs reaching up to 37°C (99°F) and lows dropping to around 5°C (41°F).
JanFebMarAprMayJunJulAugSepOctNovDec706663564944434450576066
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 total precipitation amount is 76 mm (3.0 in) spread over a period of 10 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 76 mm (3.0 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec4472113232628334635578876
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 62%. With an average temperature of 19°C (66°F), this humidity feels like a balmy embrace, making travel pleasant, yet slightly muggy, urging you to stay hydrated and seek shade during midday excursions.

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 62%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec55%60%68%74%78%78%79%74%69%58%53%62%
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 an alarming 15, which falls into the extreme Exposure Category. With a time to burn of just 10 minutes, it's crucial to take precautions. For detailed information, 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 15, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec151412864468111315
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 Weather21°C (70°F)44 mm (1.7 inches)55%extreme
February Weather19°C (66°F)72 mm (2.8 inches)60%extreme
March Weather17°C (63°F)113 mm (4.4 inches)68%extreme
April Weather13°C (56°F)23 mm (0.9 inches)74%very high
May Weather9°C (49°F)26 mm (1.0 inches)78%high
June Weather7°C (44°F)28 mm (1.1 inches)78%moderate
July Weather6°C (43°F)33 mm (1.3 inches)79%moderate
August Weather6°C (44°F)46 mm (1.8 inches)74%high
September Weather10°C (50°F)35 mm (1.4 inches)69%very high
October Weather14°C (57°F)57 mm (2.3 inches)57%extreme
November Weather16°C (61°F)88 mm (3.5 inches)53%extreme
December Weather19°C (66°F)76 mm (3.0 inches)62%extreme

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