December Weather in Washington, United States

Last updated: June 24, 2025

In Washington, United States, the average temperature in December hovers around 2°C (36°F). However, expect a temperature range that can dip as low as -13°C (9°F) and soar up to 17°C (63°F). During this month, you're likely to encounter precipitation of about 109 mm (4.3 in) spread over 10 days, contributing to a high average humidity of 85%. Be prepared for a crisp, damp experience!

December Temperature in Washington

In December in Washington, the average temperature is 2°C (36°F). Maximum temperatures can reach 17°C (63°F), while minimums can drop as low as -13°C (9°F). Be prepared for a wide range of temperatures when traveling during this month.

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 (36°F), with highs reaching up to 17°C (63°F) and lows dropping to around -13°C (9°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 109 mm (4.3 in) spread over 10 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 109 mm (4.3 inches) of precipitation spread over approximately 10 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 85%. With an average temperature of 2°C (36°F), this humidity feels like an icy blanket clinging to your skin, making travel challenging as the cold dampness seeps into your bones and fogs your breath.

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 85%, 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	0°C (32°F)	72 mm (2.8 inches)	87%	moderate
February Weather	2°C (35°F)	105 mm (4.2 inches)	85%	moderate
March Weather	5°C (41°F)	101 mm (4.0 inches)	85%	high
April Weather	11°C (51°F)	108 mm (4.2 inches)	83%	very high
May Weather	16°C (61°F)	134 mm (5.3 inches)	75%	very high
June Weather	21°C (70°F)	100 mm (3.9 inches)	73%	very high
July Weather	25°C (77°F)	128 mm (5.0 inches)	65%	very high
August Weather	23°C (74°F)	136 mm (5.4 inches)	62%	very high
September Weather	20°C (68°F)	103 mm (4.1 inches)	66%	very high
October Weather	14°C (58°F)	130 mm (5.1 inches)	79%	high
November Weather	6°C (43°F)	89 mm (3.5 inches)	87%	moderate
December Weather	2°C (36°F)	109 mm (4.3 inches)	85%	low