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December Weather in Portland, Australia

Last updated: August 22, 2025

In Portland, Australia, the average temperature in December is a mild 16°C (61°F). Expect a range of temperatures, with a minimum dipping to 9°C (48°F) and soaring up to a scorching 36°C (97°F). Be prepared for some rain, as 44 mm (1.7 in) of precipitation can be expected over 6 days. The average humidity hovers around a comfortable 76%, making this month a distinctive blend of warmth and moisture.

December Temperature in Portland

In December in Portland, the average temperature is 16°C (61°F), with maximums reaching 36°C (97°F) and minimums dipping as low as 9°C (48°F). It's advisable to pack layers to ensure comfort while exploring the varied temperatures.

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 36°C (97°F) and lows dropping to around 9°C (48°F).
JanFebMarAprMayJunJulAugSepOctNovDec646363595653525253555861
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 44 mm (1.7 in) spread over 6 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 44 mm (1.7 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec32313652928112211386756844
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 76%. With an average temperature of 16°C (61°F), this humidity feels like a warm embrace that makes traveling feel slightly heavy yet refreshing, often prompting you to seek shade or indulge in ice-cold drinks to stay comfortable.

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 76%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%75%76%76%79%78%78%77%77%76%76%76%
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 is 14, which corresponds to an extreme Exposure Category. The time to burn is just 10 minutes, so it's crucial to take precautions. For the detailed hourly UV index in Portland, you can check here.

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 14, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec13121074334791114
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 Weather18°C (64°F)32 mm (1.3 inches)76%extreme
February Weather17°C (63°F)31 mm (1.2 inches)75%extreme
March Weather17°C (63°F)35 mm (1.4 inches)76%very high
April Weather15°C (60°F)51 mm (2.0 inches)76%high
May Weather13°C (56°F)92 mm (3.6 inches)79%moderate
June Weather11°C (53°F)81 mm (3.2 inches)78%moderate
July Weather11°C (52°F)122 mm (4.8 inches)78%moderate
August Weather11°C (52°F)113 mm (4.4 inches)77%moderate
September Weather12°C (54°F)86 mm (3.4 inches)76%high
October Weather13°C (56°F)74 mm (2.9 inches)76%very high
November Weather15°C (59°F)68 mm (2.7 inches)76%extreme
December Weather16°C (61°F)44 mm (1.7 inches)76%extreme

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