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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 13°C (56°F). However, be prepared for a temperature range that can dip to as low as -2°C (28°F) and soar to a warm 29°C (85°F). Expect rainfall as well, with an average precipitation of 113 mm (4.5 in) spread across 11 days. Don't forget, the average humidity is a high 88%, making for a pleasantly moist atmosphere.

December Temperature in Washington

In December in Washington, the average temperature is 13°C (56°F), with maximums reaching 29°C (85°F) and minimums dropping as low as -2°C (28°F). This variation in temperature makes it essential for travelers to pack accordingly for both warm and chilly conditions.

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 13°C (56°F), with highs reaching up to 29°C (85°F) and lows dropping to around -2°C (28°F).
JanFebMarAprMayJunJulAugSepOctNovDec535864687681828279726056
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 total precipitation amount is 113 mm (4.5 in), spread over a period of 11 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 113 mm (4.5 inches) of precipitation spread over approximately 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec1091088215515714817817012111678113
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 88%. With an average temperature of 13°C (56°F), this humidity feels like a thick, warm blanket wrapping around you, making outdoor adventures sticky and challenging.

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 88%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec83%83%80%81%81%78%79%79%79%77%85%88%
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 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 Washington.

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 5, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec589111112121210965
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 Weather11°C (53°F)109 mm (4.3 inches)83%moderate
February Weather14°C (58°F)108 mm (4.3 inches)83%very high
March Weather18°C (65°F)82 mm (3.2 inches)80%very high
April Weather20°C (68°F)155 mm (6.1 inches)81%extreme
May Weather25°C (77°F)157 mm (6.2 inches)81%extreme
June Weather27°C (81°F)148 mm (5.8 inches)78%extreme
July Weather28°C (83°F)178 mm (7.0 inches)79%extreme
August Weather28°C (82°F)170 mm (6.7 inches)79%extreme
September Weather26°C (80°F)121 mm (4.8 inches)79%very high
October Weather22°C (72°F)116 mm (4.5 inches)77%very high
November Weather15°C (60°F)78 mm (3.1 inches)85%high
December Weather13°C (56°F)113 mm (4.5 inches)88%moderate

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