December Weather in Swansea, United States

Last updated: June 24, 2025

In December, the average temperature in Swansea, United States hovers around 10°C (51°F). You can expect a minimum drop to -6°C (21°F), while the maximum can reach a warm 28°C (83°F). Throughout the month, average precipitation accumulates to 129 mm (5.1 in) over about 10 days, and the air is quite humid, with an average humidity level of 87%.

December Temperature in Swansea

In December in Swansea, the average temperature is 10°C (51°F). Maximums can reach 28°C (83°F) while minimums can drop as low as -6°C (21°F). Travelers should be prepared for a wide range of temperatures and pack accordingly.

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

The chart illustrates December temperature patterns in Swansea, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Swansea, December typically has an average temperature of 10°C (51°F), with highs reaching up to 28°C (83°F) and lows dropping to around -6°C (21°F).

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

December Precipitation in Swansea

In Swansea in December, the precipitation amount is 129 mm (5.1 in) over a span of 10 days.

December Precipitation Trends in Swansea

The chart displays monthly precipitation patterns in Swansea, 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 Swansea, December typically receives around 129 mm (5.1 inches) of precipitation spread over approximately 10 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 Swansea

In Swansea in December humidity is 87%. With an average temperature of 10°C (51°F), this humidity feels like a heavy blanket enveloping you, making outdoor activities uncomfortable and sticky, and often requiring frequent breaks to stay hydrated and cool.

December Average Humidity in Swansea

This chart illustrates the average monthly humidity levels in Swansea, 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 Swansea 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 Swansea

In Swansea in December, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in Swansea for better planning.

Maximum UV Index Levels in Swansea for December

The chart shows the monthly maximum UV Index (UVI) for Swansea 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 Swansea typically reaches 4, which falls under the moderate exposure category.

Data source: Swansea 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 Swansea Compares to Other Months

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

This table compares monthly weather conditions in Swansea, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	9°C (49°F)	83 mm (3.3 inches)	86%	moderate
February Weather	12°C (54°F)	100 mm (3.9 inches)	81%	high
March Weather	15°C (58°F)	76 mm (3.0 inches)	81%	very high
April Weather	19°C (66°F)	112 mm (4.4 inches)	79%	very high
May Weather	23°C (74°F)	105 mm (4.2 inches)	75%	extreme
June Weather	26°C (79°F)	121 mm (4.8 inches)	75%	extreme
July Weather	27°C (82°F)	154 mm (6.1 inches)	80%	extreme
August Weather	27°C (81°F)	141 mm (5.6 inches)	81%	extreme
September Weather	25°C (77°F)	98 mm (3.9 inches)	83%	very high
October Weather	20°C (69°F)	71 mm (2.8 inches)	78%	very high
November Weather	13°C (55°F)	61 mm (2.4 inches)	85%	high
December Weather	10°C (51°F)	129 mm (5.1 inches)	87%	moderate