nomadseason

December Weather in Washington, United States

Last updated: June 24, 2025

In December, the average temperature in Washington, United States hovers around 4°C (39°F), with a minimum of -10°C (15°F) and a maximum reaching 19°C (67°F). Expect a bit of rain, as precipitation averages 35 mm (1.4 in) over about 6 days. With an average humidity of 80%, it's advisable to dress warmly and be prepared for the damp conditions!

December Temperature in Washington

In December in Washington, the average temperature is 4°C (39°F). Maximum can reach 19°C (67°F) and minimum can be as low as -10°C (15°F). It's a great time to visit if you enjoy cool weather and are prepared for a range of temperatures.

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 4°C (39°F), with highs reaching up to 19°C (67°F) and lows dropping to around -10°C (15°F).
JanFebMarAprMayJunJulAugSepOctNovDec384149596780858375584839
Data source: Temperature data for Washington generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
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 35 mm (1.4 in) spread over a period of 6 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 35 mm (1.4 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec484248121619105132935
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

December Humidity in Washington

In Washington in December, humidity is 80%. With an average temperature of 4°C (39°F), this humidity feels like a damp chill that seeps into your bones, making travel uncomfortable and requiring extra layers to stay warm while navigating through the misty streets.

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 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec80%82%72%62%45%34%30%31%47%62%77%80%
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 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in Washington for better planning.

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 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec468101112121110754
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 Weather3°C (38°F)48 mm (1.9 inches)80%moderate
February Weather5°C (41°F)42 mm (1.7 inches)82%high
March Weather9°C (49°F)48 mm (1.9 inches)72%very high
April Weather15°C (59°F)12 mm (0.5 inches)62%very high
May Weather19°C (67°F)16 mm (0.6 inches)45%extreme
June Weather27°C (80°F)1 mm (0.0 inches)34%extreme
July Weather29°C (85°F)9 mm (0.3 inches)30%extreme
August Weather28°C (83°F)10 mm (0.4 inches)31%extreme
September Weather24°C (75°F)5 mm (0.2 inches)47%very high
October Weather15°C (59°F)13 mm (0.5 inches)62%high
November Weather9°C (49°F)29 mm (1.1 inches)77%moderate
December Weather4°C (39°F)35 mm (1.4 inches)80%moderate

Compare Washington's Climate with Cities Worldwide