December Weather in Rosslyn, United States

Last updated: June 24, 2025

In Rosslyn, United States, the average temperature in December hovers around 5°C (41°F). Temperature extremes can range from a chilly -10°C (13°F) to a pleasant 20°C (69°F). Expect 93 mm (3.7 in) of precipitation over approximately 9 days, contributing to an average humidity of 84%. 🌧️✨

December Temperature in Rosslyn

In December in Rosslyn, the average temperature is 5°C (41°F), with maximums reaching up to 20°C (69°F) and minimums dropping as low as -10°C (13°F). It's advisable to pack layers to prepare for the wide range of temperatures you'll encounter while traveling.

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

The chart illustrates December temperature patterns in Rosslyn, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Rosslyn, December typically has an average temperature of 5°C (41°F), with highs reaching up to 20°C (69°F) and lows dropping to around -10°C (13°F).

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

December Precipitation in Rosslyn

In Rosslyn in December, the precipitation amount is 93 mm (3.7 in) over the course of 9 days.

December Precipitation Trends in Rosslyn

The chart displays monthly precipitation patterns in Rosslyn, 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 Rosslyn, December typically receives around 93 mm (3.7 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 Rosslyn

In Rosslyn in December humidity is 84%. With an average temperature of 5°C (41°F), this humidity feels like a damp chill that seeps into your bones, making traveling uncomfortable as you navigate through the cold, heavy air that clings to your skin.

December Average Humidity in Rosslyn

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

In Rosslyn 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 Rosslyn, you can check the information here.

Maximum UV Index Levels in Rosslyn for December

The chart shows the monthly maximum UV Index (UVI) for Rosslyn 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 Rosslyn typically reaches 3, which falls under the moderate exposure category.

Data source: Rosslyn 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 Rosslyn Compares to Other Months

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

This table compares monthly weather conditions in Rosslyn, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	3°C (37°F)	61 mm (2.4 inches)	84%	moderate
February Weather	5°C (41°F)	98 mm (3.9 inches)	83%	moderate
March Weather	8°C (46°F)	87 mm (3.4 inches)	83%	high
April Weather	14°C (57°F)	100 mm (4.0 inches)	81%	very high
May Weather	19°C (66°F)	127 mm (5.0 inches)	78%	very high
June Weather	24°C (75°F)	118 mm (4.7 inches)	79%	very high
July Weather	27°C (81°F)	157 mm (6.2 inches)	74%	very high
August Weather	25°C (77°F)	140 mm (5.5 inches)	72%	very high
September Weather	22°C (72°F)	95 mm (3.8 inches)	75%	very high
October Weather	17°C (62°F)	104 mm (4.1 inches)	81%	high
November Weather	8°C (47°F)	81 mm (3.2 inches)	85%	moderate
December Weather	5°C (41°F)	93 mm (3.7 inches)	84%	moderate