December Weather in Thornhill, South Africa

Last updated: August 31, 2025

In December, the average temperature in Thornhill, South Africa hovers around 20°C (67°F). Expect chilling lows of 12°C (55°F) and balmy highs reaching up to 31°C (88°F). During this time, the region experiences approximately 48 mm (1.9 in) of precipitation over 9 days, with an average humidity level of 78%. Be prepared for a mix of warm sunshine and occasional showers!

December Temperature in Thornhill

In December in Thornhill, the average temperature is 20°C (67°F). The maximum can reach 31°C (88°F), and the minimum can be as low as 12°C (55°F). This pleasant climate makes it an ideal time for outdoor activities and exploration.

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

The chart illustrates December temperature patterns in Thornhill, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Thornhill, December typically has an average temperature of 20°C (67°F), with highs reaching up to 31°C (88°F) and lows dropping to around 12°C (55°F).

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

December Precipitation in Thornhill

In Thornhill in December, the total precipitation amount is 48 mm (1.9 in) spread over 9 days.

December Precipitation Trends in Thornhill

The chart displays monthly precipitation patterns in Thornhill, 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 Thornhill, December typically receives around 48 mm (1.9 inches) of precipitation spread over approximately 9 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 Thornhill

In Thornhill in December humidity is 78%. With an average temperature of 20°C (67°F), this humidity feels like walking through a warm, thick blanket, making travel a bit sticky and requiring frequent breaks to find shade and cool refreshments.

December Average Humidity in Thornhill

This chart illustrates the average monthly humidity levels in Thornhill, 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 Thornhill is approximately 78%, 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 Thornhill

In Thornhill in December, the maximum UV index is 14, which corresponds to an extreme Exposure Category. The time to burn is just 10 minutes, so it's crucial to take precautions. For the detailed hourly UV index in Thornhill, you can check here.

Maximum UV Index Levels in Thornhill for December

The chart shows the monthly maximum UV Index (UVI) for Thornhill 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 Thornhill typically reaches 14, which falls under the extreme exposure category.

Data source: Thornhill 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 Thornhill Compares to Other Months

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

This table compares monthly weather conditions in Thornhill, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	21°C (70°F)	28 mm (1.1 inches)	79%	extreme
February Weather	21°C (70°F)	48 mm (1.9 inches)	81%	extreme
March Weather	20°C (69°F)	43 mm (1.7 inches)	83%	extreme
April Weather	18°C (65°F)	28 mm (1.1 inches)	80%	very high
May Weather	17°C (63°F)	31 mm (1.2 inches)	76%	moderate
June Weather	16°C (62°F)	19 mm (0.7 inches)	72%	moderate
July Weather	16°C (60°F)	33 mm (1.3 inches)	74%	moderate
August Weather	15°C (59°F)	53 mm (2.1 inches)	72%	high
September Weather	16°C (61°F)	42 mm (1.6 inches)	75%	very high
October Weather	17°C (63°F)	38 mm (1.5 inches)	76%	extreme
November Weather	18°C (65°F)	47 mm (1.9 inches)	76%	extreme
December Weather	20°C (67°F)	48 mm (1.9 inches)	78%	extreme