December Weather in Washington, United States

Last updated: June 24, 2025

In December, the average temperature in Washington, United States hovers around -5°C (24°F), with extremes that can plummet to -28°C (-18°F) and reach a maximum of 14°C (57°F). Expect 88 mm (3.4 in) of precipitation spread across 13 days, contributing to an average humidity of 84%. Stay prepared for a chilly and damp environment!

December Temperature in Washington

In December in Washington, the average temperature is -5°C (24°F). Maximums can reach 14°C (57°F), while minimums can drop as low as -28°C (-18°F). Travelers should be prepared for a wide range of temperatures, ensuring they pack layers for both warmer days and frigid nights.

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 -5°C (24°F), with highs reaching up to 14°C (57°F) and lows dropping to around -28°C (-18°F).

Data source: Temperature data for Washington generated using information from the Copernicus Climate Change Service.

December Precipitation in Washington

In Washington in December, the precipitation amount is 88 mm (3.4 in) occurring over 13 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 88 mm (3.4 inches) of precipitation spread over approximately 13 days.

Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

December Humidity in Washington

In Washington in December, humidity is 84%. With an average temperature of -5°C (24°F), this humidity feels like an icy blanket wrapped around you, making the air feel even colder and more biting, which can be quite uncomfortable for traveling.

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.

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 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 Washington, you can visit 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 2, which falls under the low exposure category.

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.
	Temperature	Precipitation	Humidity	UV
January Weather	-7°C (19°F)	77 mm (3.0 inches)	89%	low
February Weather	-6°C (22°F)	80 mm (3.2 inches)	88%	moderate
March Weather	-2°C (29°F)	71 mm (2.8 inches)	86%	moderate
April Weather	5°C (42°F)	117 mm (4.6 inches)	84%	very high
May Weather	12°C (55°F)	96 mm (3.8 inches)	76%	very high
June Weather	17°C (64°F)	97 mm (3.8 inches)	72%	very high
July Weather	20°C (69°F)	140 mm (5.5 inches)	66%	very high
August Weather	19°C (67°F)	98 mm (3.9 inches)	64%	very high
September Weather	15°C (60°F)	71 mm (2.8 inches)	72%	high
October Weather	9°C (48°F)	141 mm (5.6 inches)	81%	moderate
November Weather	1°C (33°F)	104 mm (4.1 inches)	87%	moderate
December Weather	-5°C (24°F)	88 mm (3.4 inches)	84%	low