December Weather in Upland, United States

Last updated: June 24, 2025

In Upland, United States, the average temperature in December hovers around 12°C (54°F). Expect a minimum of 2°C (36°F) and a comfortable maximum of 27°C (81°F). During this month, you can anticipate about 79 mm (3.1 in) of precipitation spread across 5 days, with an average humidity level of 71%.

December Temperature in Upland

In December in Upland, the average temperature is 12°C (54°F). Maximum temperatures can reach 27°C (81°F) while minimums can drop as low as 2°C (36°F). Be sure to pack layers to enjoy the pleasant days and stay warm during the cooler nights!

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

The chart illustrates December temperature patterns in Upland, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Upland, December typically has an average temperature of 12°C (54°F), with highs reaching up to 27°C (81°F) and lows dropping to around 2°C (36°F).

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

December Precipitation in Upland

In Upland in December, the precipitation amount is 79 mm (3.1 in) over a span of 5 days.

December Precipitation Trends in Upland

The chart displays monthly precipitation patterns in Upland, 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 Upland, December typically receives around 79 mm (3.1 inches) of precipitation spread over approximately 5 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 Upland

In Upland in December humidity is 71%. With an average temperature of 12°C (54°F), this humidity feels like a damp chill that clings to your skin, making it essential to dress in layers while exploring the area, as the cool air can be refreshing yet slightly uncomfortable without proper attire for outdoor activities.

December Average Humidity in Upland

This chart illustrates the average monthly humidity levels in Upland, 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 Upland is approximately 71%, 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 Upland

In Upland 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 Upland for better planning.

Maximum UV Index Levels in Upland for December

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

Data source: Upland 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 Upland Compares to Other Months

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

This table compares monthly weather conditions in Upland, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	12°C (54°F)	80 mm (3.1 inches)	74%	moderate
February Weather	12°C (55°F)	70 mm (2.8 inches)	79%	high
March Weather	14°C (57°F)	76 mm (3.0 inches)	75%	very high
April Weather	16°C (62°F)	27 mm (1.1 inches)	70%	very high
May Weather	18°C (64°F)	17 mm (0.7 inches)	70%	very high
June Weather	21°C (70°F)	1 mm (0.0 inches)	72%	extreme
July Weather	24°C (76°F)	1 mm (0.1 inches)	73%	extreme
August Weather	25°C (77°F)	2 mm (0.1 inches)	69%	very high
September Weather	23°C (74°F)	3 mm (0.1 inches)	68%	very high
October Weather	20°C (68°F)	12 mm (0.5 inches)	67%	high
November Weather	16°C (61°F)	26 mm (1.0 inches)	68%	moderate
December Weather	12°C (54°F)	79 mm (3.1 inches)	71%	moderate