December Weather in Union, United States

Last updated: June 24, 2025

The average temperature in Union, United States during December is a brisk 5°C (42°F), with lows reaching -5°C (23°F) and highs peaking at 13°C (55°F). Expect precipitation of about 250 mm (9.9 in) over the course of 20 days, and prepare for a humidity level that hovers around 87%—perfect for cozy indoor activities!

December Temperature in Union

In December in Union, the average temperature is 5°C (42°F). Maximum temperatures can reach 13°C (55°F), while minimums can drop as low as -5°C (23°F). Be prepared for a chilly adventure, and pack accordingly to fully enjoy your time in Union.

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

The chart illustrates December temperature patterns in Union, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Union, December typically has an average temperature of 5°C (42°F), with highs reaching up to 13°C (55°F) and lows dropping to around -5°C (23°F).

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

December Precipitation in Union

In Union in December, the precipitation amount is 250 mm (9.9 in) spread over 20 days.

December Precipitation Trends in Union

The chart displays monthly precipitation patterns in Union, 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 Union, December typically receives around 250 mm (9.9 inches) of precipitation spread over approximately 20 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 Union

In Union in December humidity is 87%. With an average temperature of 5°C (42°F), this humidity feels like a damp chill that seeps into your bones, making outdoor activities less enjoyable and travel less inviting as the air becomes heavy and oppressive.

December Average Humidity in Union

This chart illustrates the average monthly humidity levels in Union, 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 Union is approximately 87%, 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 Union

In Union 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 Union, you can visit Hourly UV Index in Union.

Maximum UV Index Levels in Union for December

The chart shows the monthly maximum UV Index (UVI) for Union 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 Union typically reaches 2, which falls under the low exposure category.

Data source: Union 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 Union Compares to Other Months

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

This table compares monthly weather conditions in Union, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	5°C (42°F)	256 mm (10.1 inches)	86%	low
February Weather	5°C (41°F)	171 mm (6.7 inches)	84%	moderate
March Weather	7°C (45°F)	148 mm (5.8 inches)	85%	moderate
April Weather	10°C (49°F)	124 mm (4.9 inches)	83%	high
May Weather	13°C (56°F)	60 mm (2.4 inches)	84%	very high
June Weather	16°C (61°F)	49 mm (1.9 inches)	84%	very high
July Weather	19°C (66°F)	9 mm (0.4 inches)	82%	very high
August Weather	19°C (66°F)	14 mm (0.6 inches)	73%	very high
September Weather	16°C (61°F)	95 mm (3.7 inches)	74%	high
October Weather	11°C (52°F)	168 mm (6.6 inches)	83%	moderate
November Weather	8°C (47°F)	243 mm (9.6 inches)	86%	moderate
December Weather	5°C (42°F)	250 mm (9.9 inches)	87%	low