December Weather in Union, United States

Last updated: June 24, 2025

In Union, United States, the average temperature in December hovers around -2°C (28°F). However, be prepared for extremes, with temperatures plummeting as low as -24°C (-11°F) and occasionally rising to a maximum of 12°C (53°F). During this month, expect 94 mm (3.7 in) of precipitation spread over 16 days, contributing to an average humidity level of 87%. Stay dry and bundled up!

December Temperature in Union

In December in Union, the average temperature is -2°C (28°F). Maximums can reach 12°C (53°F) and minimums can be as low as -24°C (-11°F). Travelers should be prepared for a wide range of temperatures, so dressing in layers is essential for comfort.

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 -2°C (28°F), with highs reaching up to 12°C (53°F) and lows dropping to around -24°C (-11°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 94 mm (3.7 in) over a span of 16 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 94 mm (3.7 inches) of precipitation spread over approximately 16 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 Union

In Union in December, humidity is 87%. With an average temperature of -2°C (28°F), this humidity feels like a damp chill that seeps into your bones, making outdoor exploration less enjoyable and requiring extra layers to stay warm and comfortable while traveling.

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	-3°C (27°F)	86 mm (3.4 inches)	86%	moderate
February Weather	-3°C (27°F)	132 mm (5.2 inches)	86%	moderate
March Weather	2°C (36°F)	89 mm (3.5 inches)	85%	high
April Weather	5°C (42°F)	83 mm (3.3 inches)	83%	very high
May Weather	10°C (49°F)	75 mm (2.9 inches)	77%	very high
June Weather	14°C (58°F)	41 mm (1.6 inches)	81%	very high
July Weather	20°C (68°F)	2 mm (0.1 inches)	76%	extreme
August Weather	19°C (67°F)	16 mm (0.6 inches)	60%	very high
September Weather	14°C (57°F)	33 mm (1.3 inches)	58%	very high
October Weather	6°C (44°F)	67 mm (2.6 inches)	75%	moderate
November Weather	2°C (35°F)	76 mm (3.0 inches)	85%	moderate
December Weather	-2°C (28°F)	94 mm (3.7 inches)	87%	low