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December Weather in Union, United States

Last updated: June 24, 2025

In Union, United States, the average temperature in December hovers around 9°C (49°F), with a minimum plummeting to -6°C (21°F) and a potential peak of 26°C (79°F). Expect about 130 mm (5.1 in) of precipitation over 9 days during the month, contributing to an average humidity of 87%.

December Temperature in Union

In December in Union, the average temperature is 9°C (49°F), with maximums reaching 26°C (79°F) and minimums dropping as low as -6°C (21°F). This wide range of temperatures suggests travelers should be prepared for both warm days and chilly nights while exploring the area.

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 9°C (49°F), with highs reaching up to 26°C (79°F) and lows dropping to around -6°C (21°F).
JanFebMarAprMayJunJulAugSepOctNovDec465155637277817975665248
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 130 mm (5.1 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 130 mm (5.1 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec9512390108115901131271159796130
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 87%. With an average temperature of 9°C (49°F), this humidity feels like a damp blanket wrapping around you, making travel uncomfortable and leaving you yearning for a dry breeze to refresh your spirit.

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.
JanFebMarAprMayJunJulAugSepOctNovDec86%85%84%82%83%82%80%74%75%79%87%87%
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.
JanFebMarAprMayJunJulAugSepOctNovDec46810111111109863
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 Weather8°C (46°F)95 mm (3.7 inches)86%moderate
February Weather10°C (51°F)123 mm (4.8 inches)85%high
March Weather13°C (56°F)90 mm (3.6 inches)84%very high
April Weather17°C (63°F)108 mm (4.2 inches)82%very high
May Weather22°C (72°F)115 mm (4.5 inches)83%extreme
June Weather25°C (77°F)90 mm (3.5 inches)82%extreme
July Weather27°C (81°F)113 mm (4.5 inches)80%extreme
August Weather26°C (79°F)127 mm (5.0 inches)74%very high
September Weather24°C (76°F)115 mm (4.5 inches)75%very high
October Weather19°C (67°F)97 mm (3.8 inches)79%very high
November Weather11°C (53°F)96 mm (3.8 inches)87%high
December Weather9°C (49°F)130 mm (5.1 inches)87%moderate

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