December Weather in Northwest, United States

Last updated: June 24, 2025

In Northwest, United States, the average temperature in December hovers around 10°C (51°F), creating a crisp climate perfect for exploring. Expect minimum temperatures to dip to -6°C (22°F), while the mercury can peak at a cozy 25°C (77°F). During this month, precipitation averages 124 mm (4.9 in) over 9 days, contributing to the lush landscapes, and humidity levels remain high at 86%, adding to the atmosphere. Whether you’re bundling up or enjoying mild days, Northwest offers a unique experience this time of year!

December Temperature in Northwest

In December in Northwest, the average temperature is 10°C (51°F). Maximum temperatures can reach 25°C (77°F), while the minimum can drop as low as -6°C (22°F). This variation in temperature makes Northwest an ideal destination for travelers seeking both mild weather and the possibility of crisp, cooler days.

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

The chart illustrates December temperature patterns in Northwest, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Northwest, December typically has an average temperature of 10°C (51°F), with highs reaching up to 25°C (77°F) and lows dropping to around -6°C (22°F).

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

December Precipitation in Northwest

In Northwest in December, the precipitation amount is 124 mm (4.9 in) over the course of 9 days.

December Precipitation Trends in Northwest

The chart displays monthly precipitation patterns in Northwest, 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 Northwest, December typically receives around 124 mm (4.9 inches) of precipitation spread over approximately 9 days.

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

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Millimeters (mm) Inches (in)

December Humidity in Northwest

In Northwest in December humidity is 86%. With an average temperature of 10°C (51°F), this humidity feels like a cool, damp blanket enveloping you, making traveling feel invigorating yet slightly uncomfortable without the right layers.

December Average Humidity in Northwest

This chart illustrates the average monthly humidity levels in Northwest, 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 Northwest is approximately 86%, 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 Northwest

In Northwest 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 Northwest for better planning.

Maximum UV Index Levels in Northwest for December

The chart shows the monthly maximum UV Index (UVI) for Northwest 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 Northwest typically reaches 4, which falls under the moderate exposure category.

Data source: Northwest 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 Northwest Compares to Other Months

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

This table compares monthly weather conditions in Northwest, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	9°C (48°F)	70 mm (2.8 inches)	85%	moderate
February Weather	12°C (53°F)	93 mm (3.7 inches)	82%	high
March Weather	13°C (56°F)	70 mm (2.8 inches)	81%	very high
April Weather	18°C (64°F)	94 mm (3.7 inches)	80%	very high
May Weather	22°C (72°F)	120 mm (4.7 inches)	81%	extreme
June Weather	25°C (77°F)	160 mm (6.3 inches)	81%	extreme
July Weather	27°C (80°F)	171 mm (6.7 inches)	81%	extreme
August Weather	26°C (80°F)	205 mm (8.1 inches)	80%	very high
September Weather	24°C (76°F)	193 mm (7.6 inches)	79%	very high
October Weather	20°C (69°F)	64 mm (2.5 inches)	80%	very high
November Weather	13°C (55°F)	110 mm (4.3 inches)	85%	high
December Weather	10°C (51°F)	124 mm (4.9 inches)	86%	moderate