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December Weather in Washington, United States

Last updated: June 24, 2025

In December, the average temperature in Washington, United States hovers around a chilly 2°C (35°F). Be prepared for extreme fluctuations, as temperatures can dip as low as -18°C (0°F) or soar to a balmy 23°C (74°F). During this time, expect 28 mm (1.1 in) of precipitation over approximately 3 days, with an average humidity level of 84%. Pack accordingly!

December Temperature in Washington

In December in Washington, the average temperature is 2°C (35°F). The maximum can reach 23°C (74°F), and the minimum can be as low as -18°C (0°F). Travelers should be prepared for a wide range of temperatures and pack accordingly to fully enjoy their stay in Washington.

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

The chart illustrates December temperature patterns in Washington, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Washington, December typically has an average temperature of 2°C (35°F), with highs reaching up to 23°C (74°F) and lows dropping to around -18°C (0°F).
JanFebMarAprMayJunJulAugSepOctNovDec303044536477807772554335
Data source: Temperature data for Washington 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 Washington

In Washington in December, the precipitation amount is 28 mm (1.1 in) over the course of 3 days.

December Precipitation Trends in Washington

The chart displays monthly precipitation patterns in Washington, 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 Washington, December typically receives around 28 mm (1.1 inches) of precipitation spread over approximately 3 days.
JanFebMarAprMayJunJulAugSepOctNovDec28278761201948995671213128
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Washington

In Washington in December, humidity is 84%. With an average temperature of 2°C (35°F), this humidity feels like an uncomfortable chill that penetrates your bones, making outdoor travel quite brisk and uninviting.

December Average Humidity in Washington

This chart illustrates the average monthly humidity levels in Washington, 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 Washington is approximately 84%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%78%70%73%82%82%81%78%71%71%81%84%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Washington

In Washington in December, the maximum UV index is 3, which corresponds to a moderate Exposure Category. The time to burn is approximately 30 minutes. For more details on the hourly UV index in Washington, you can check the information here.

Maximum UV Index Levels in Washington for December

The chart shows the monthly maximum UV Index (UVI) for Washington 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 Washington typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3569101111109643
Data source: Washington 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 Washington Compares to Other Months

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

This table compares monthly weather conditions in Washington, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-1°C (30°F)28 mm (1.1 inches)76%moderate
February Weather-1°C (30°F)27 mm (1.1 inches)77%moderate
March Weather7°C (45°F)86 mm (3.4 inches)70%high
April Weather12°C (53°F)60 mm (2.4 inches)73%very high
May Weather18°C (65°F)201 mm (7.9 inches)82%very high
June Weather25°C (78°F)94 mm (3.7 inches)82%extreme
July Weather27°C (81°F)89 mm (3.5 inches)81%extreme
August Weather25°C (77°F)95 mm (3.7 inches)78%very high
September Weather22°C (72°F)67 mm (2.7 inches)71%very high
October Weather13°C (55°F)121 mm (4.8 inches)71%high
November Weather6°C (43°F)31 mm (1.2 inches)81%moderate
December Weather2°C (35°F)28 mm (1.1 inches)84%moderate

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