December Weather in Belfast, United States

Last updated: June 24, 2025

In December, the average temperature in Belfast, United States hovers around -2°C (28°F). However, be prepared for a chill as temperatures can plunge to a minimum of -22°C (-8°F) or soar to a maximum of 15°C (59°F). Rainfall is also a factor, with an average precipitation of 129 mm (5.1 in) occurring over 11 days. Don’t forget your layers, as humidity levels sit at a brisk 84%!

December Temperature in Belfast

In December in Belfast, the average temperature is -2°C (28°F). Maximum temperatures can reach 15°C (59°F), while minimums can drop as low as -22°C (-8°F). Travelers should be prepared for a wide range of temperatures and pack accordingly.

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

The chart illustrates December temperature patterns in Belfast, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Belfast, December typically has an average temperature of -2°C (28°F), with highs reaching up to 15°C (59°F) and lows dropping to around -22°C (-8°F).

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

December Precipitation in Belfast

In Belfast in December, the precipitation amount is 129 mm (5.1 in) spread over 11 days, indicating a wet period for the area.

December Precipitation Trends in Belfast

The chart displays monthly precipitation patterns in Belfast, 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 Belfast, December typically receives around 129 mm (5.1 inches) of precipitation spread over approximately 11 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 Belfast

In Belfast in December humidity is 84%. With an average temperature of -2°C (28°F), this humidity feels like a biting chill that cuts through layers of clothing, making outdoor activities uncomfortable and travel challenging.

December Average Humidity in Belfast

This chart illustrates the average monthly humidity levels in Belfast, 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 Belfast is approximately 84%, 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 Belfast

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

Maximum UV Index Levels in Belfast for December

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

Data source: Belfast 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 Belfast Compares to Other Months

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

This table compares monthly weather conditions in Belfast, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-4°C (24°F)	93 mm (3.7 inches)	88%	low
February Weather	-4°C (26°F)	88 mm (3.5 inches)	88%	moderate
March Weather	0°C (32°F)	72 mm (2.9 inches)	85%	moderate
April Weather	6°C (43°F)	131 mm (5.2 inches)	81%	high
May Weather	11°C (53°F)	90 mm (3.6 inches)	76%	very high
June Weather	17°C (63°F)	76 mm (3.0 inches)	74%	very high
July Weather	20°C (68°F)	91 mm (3.6 inches)	74%	very high
August Weather	20°C (68°F)	75 mm (3.0 inches)	74%	very high
September Weather	16°C (61°F)	77 mm (3.0 inches)	77%	high
October Weather	11°C (51°F)	130 mm (5.1 inches)	82%	moderate
November Weather	3°C (38°F)	121 mm (4.8 inches)	85%	moderate
December Weather	-2°C (28°F)	129 mm (5.1 inches)	84%	low