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December Weather in Lake Oswego, United States

Last updated: June 24, 2025

In December, the average temperature in Lake Oswego, United States hovers around 5°C (41°F). Minimum temperatures can drop to a chilly -5°C (24°F), while highs reach a pleasant 16°C (60°F). Expect 183 mm (7.2 in) of precipitation over approximately 19 days, with humidity levels averaging a notable 87%.

December Temperature in Lake Oswego

In December in Lake Oswego, the average temperature is 5°C (41°F). The maximum can reach 16°C (60°F), while the minimum can drop as low as -5°C (24°F). It's advisable to pack layers and prepare for varying conditions when traveling during this time.

December Weather in Lake Oswego: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Lake Oswego, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Lake Oswego, December typically has an average temperature of 5°C (41°F), with highs reaching up to 16°C (60°F) and lows dropping to around -5°C (24°F).
JanFebMarAprMayJunJulAugSepOctNovDec424146515864697064534641
Data source: Temperature data for Lake Oswego 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 Lake Oswego

In Lake Oswego in December, the total precipitation amount is 183 mm (7.2 in) over a span of 19 days.

December Precipitation Trends in Lake Oswego

The chart displays monthly precipitation patterns in Lake Oswego, 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 Lake Oswego, December typically receives around 183 mm (7.2 inches) of precipitation spread over approximately 19 days.
JanFebMarAprMayJunJulAugSepOctNovDec16317213511758466862105155184
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Lake Oswego

In Lake Oswego in December humidity is 87%. With an average temperature of 5°C (41°F), this humidity feels like a heavy, damp blanket enveloping you, making every step seem laborious and the chill more biting, which can be quite challenging for traveling.

December Average Humidity in Lake Oswego

This chart illustrates the average monthly humidity levels in Lake Oswego, 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 Lake Oswego is approximately 87%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%84%85%83%83%84%82%74%71%81%87%87%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Lake Oswego

In Lake Oswego in December, the maximum UV index is 2, which corresponds to a low exposure category. With this level of UV radiation, the time to burn is approximately 45 minutes. To learn more about the hourly UV index in Lake Oswego, you can visit Hourly UV Index in Lake Oswego.

Maximum UV Index Levels in Lake Oswego for December

The chart shows the monthly maximum UV Index (UVI) for Lake Oswego 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 Lake Oswego typically reaches 2, which falls under the low exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec23569101087532
Data source: Lake Oswego 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 Lake Oswego Compares to Other Months

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

This table compares monthly weather conditions in Lake Oswego, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather5°C (42°F)163 mm (6.4 inches)85%low
February Weather5°C (41°F)172 mm (6.8 inches)84%moderate
March Weather8°C (46°F)135 mm (5.3 inches)85%moderate
April Weather11°C (51°F)117 mm (4.6 inches)83%high
May Weather14°C (58°F)58 mm (2.3 inches)83%very high
June Weather18°C (64°F)46 mm (1.8 inches)83%very high
July Weather21°C (69°F)6 mm (0.2 inches)82%very high
August Weather21°C (70°F)8 mm (0.3 inches)74%very high
September Weather18°C (64°F)62 mm (2.4 inches)71%high
October Weather12°C (53°F)105 mm (4.1 inches)81%moderate
November Weather8°C (47°F)155 mm (6.1 inches)87%moderate
December Weather5°C (41°F)183 mm (7.2 inches)87%low

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