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December Weather in Union, United States

Last updated: June 24, 2025

In December, the average temperature in Union, United States hovers around 3°C (39°F), with temperatures ranging from a chilly -17°C (2°F) to a balmy 20°C (67°F). Prepare for 95 mm (3.7 in) of precipitation over approximately 9 days, contributing to the high average humidity of 86%. Embrace the unique climate this season brings!

December Temperature in Union

In December in Union, the average temperature is 3°C (39°F), with maximums reaching up to 20°C (67°F) and minimums plunging to as low as -17°C (2°F). Travelers should be prepared for a wide range of weather conditions, from chilly days to potentially warm afternoons.

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 3°C (39°F), with highs reaching up to 20°C (67°F) and lows dropping to around -17°C (2°F).
JanFebMarAprMayJunJulAugSepOctNovDec343944536268737167574338
Data source: Temperature data for Union generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

December Precipitation in Union

In Union in December, the precipitation amount is 95 mm (3.7 in) over the course of 9 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 95 mm (3.7 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec74124921131319369881021087095
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Union

In Union in December, humidity is 86%. With an average temperature of 3°C (39°F), this humidity feels like a damp chill that seeps into your bones, making outdoor activities less enjoyable and requiring extra layers for comfort while exploring.

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 86%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%87%86%84%83%83%79%66%68%78%89%86%
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 3, which corresponds to a moderate Exposure Category. The time to burn is approximately 30 minutes. For more details on the hourly UV index in Union, you can check the information here.

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 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec36810111111109753
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.
 TemperaturePrecipitationHumidityUV
January Weather1°C (34°F)74 mm (2.9 inches)87%moderate
February Weather4°C (40°F)124 mm (4.9 inches)87%high
March Weather7°C (44°F)92 mm (3.6 inches)86%very high
April Weather12°C (53°F)113 mm (4.5 inches)84%very high
May Weather17°C (62°F)131 mm (5.2 inches)83%extreme
June Weather20°C (69°F)93 mm (3.7 inches)83%extreme
July Weather23°C (73°F)69 mm (2.7 inches)79%extreme
August Weather22°C (72°F)88 mm (3.5 inches)66%very high
September Weather19°C (67°F)101 mm (4.0 inches)68%very high
October Weather14°C (57°F)108 mm (4.2 inches)78%high
November Weather6°C (43°F)70 mm (2.7 inches)89%moderate
December Weather3°C (39°F)95 mm (3.7 inches)86%moderate

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